Cushion bearing implants for load bearing applications

ABSTRACT

The present invention seeks to provide improved joint implants and methods relating to joint implantation.

REFERENCE TO RELATED APPLICATIONS

This application is partially based upon and claims priority from U.S.Provisional Patent Application Ser. No. 60/338,349 filed Dec. 4, 2001and entitled “RESURFACING FEMORAL HEAD”; U.S. Provisional PatentApplication Ser. No. 60/351,755 filed Jan. 24, 2002 and entitled“CONFIGURATION-PATTERN, TEXTURE, REINFORCEMENT AND COATING ON PROSTHESISSURFACE ENGAGING BONE; AND SURFACE TREATMENT OF ARTICULATING SURFACE”and U.S. Provisional Patent Application Ser. No. 60/383,483 filed May23, 2002 and entitled “JOINT IMPLANTS SYSTEM AND METHODOLOGY ANDIMPLANTS AND TOOLS USEFUL THEREWITH”.

FIELD OF THE INVENTION

The present invention relates generally to joint implants and methodsrelating thereto.

BACKGROUND OF THE INVENTION

The following patents are believed to be relevant to the subject matterof this application:

U.S. Pat. Nos. 5,201,881; 5,011,497; 4,279,041; 5,080,675; 4,650,491;3,938,198; 4,292,695; 4,624,674; 2,765,787; 4.735,625; 5,370,699;5,641,323; 5,323,765; 5,658,345; 3,875,594; 3,938,198; 4,292,695;4,344,193; 4,570,270; 4,650,491; 4,279,041; 4,661,112; 4,662,889;4,664,668; 4,715,859; 4,795,470; 4,795,474; 4,808,186; 4,813,962;4,822,365; 4,888,020; 4,904,269; 4,908,035; 4,919,674; 4,919,678;4,936,856; 4,938,771; 4,938,773; 4,950,298; 4,955,912; 4,955,919;4,963,153; 4,963,154; 4,997,447; 5,002,581; 5,019,107; 5,041,140;5,049,393; 5,080,677; 5,108,446; 5,108,451; 5,116,374; 5,133,763;5,146,933; 5,147,406. 5,151,521; 5,156,631; 5,171,276; 5,181,925;5,197,987; 5,197,989; 5,201,881; 5,201,882; 5,217,498; 5,217,499;5,222,985; 5,282,868; 5,290,314; 5,314,478; 5,314,494; 5,316,550;5,326,376; 5,330,534; 5,314,493; 5,336,268; 5,344,459; 5,358,525;5,370,699; 5,376,064; 5,376,125; 5,387,244; 5,389,107; 5,405,403;5,405,411; 5,415,662; 5,425,779; 5,448,489; 5,458,643; 5,458,651;5,489,311; 5,491,882; 5,507,814; 5,507,818; 5,507,820; 5,507,823;5,507,830; 5,507,833; 5,507,836; 5,514,182; 5,514,184; 5,522,904;5,507,835; 5,246,461; 5,364,839; 5,376,120; 5,393,739; 5,480,449;5,510,418; 5,522,894; 4,892,551; 5,660,225; 4,089,071; 5,281,226;5,443,383; 5,480,437; 5,032,134; 4,997,444; 5,002,579; 5,443,512;5,133,762; 5,080,678; 5,944,759; 5,944,758; 5,944,757; 5,944,756;5,938,702; 5,935,174; 5,935,175; 5,935,173; 5,935,172; 5,935,171;5,931,871; 5,931,870; 5,928,289; 5,928,288; 5,928,287; 5,928,286;5,928,285; 5,919,236; 5,916,270; 5,916,269; 5,916,268; 5,913,858;5,911,759; 5,911,758; 5,910,172; 5,910,171; 5,906,644; 5,906,643;5,906,210; 5,904,720; 5,904,688; 5,902,340; 5,882,206; 5,888,204;5,879,407; 5,879,405; 5,879,404; 5,879,402; 5,879,401; 5,879,398;5,879,397; 5,879,396; 5,879,395; 5,879,393; 5,879,392; 5,879,390;5,879,387; 5,871,548; 5,871,547; 5,824,108; 5,824,107; 5,824,103;5,824,102, 5,824,101; 5,824,098; 5,800,560; 5,800,558; 5,800,557;5,800,555; 5,800,554; 5,800,553; 5,788,704; 5,782,928; 5,782,925;5,776,202; 5,766,260; 5,766,257; 5,755 811; 5,755,810; 5,755,804;5,755,801; 5,755,799; 5,743,918; 5,910,172; 5,211,666; 5,507,832;4,433,440; 5,397,359; 5,507,834; 5,314,492; 5,405,394; 5,316,550;5,314,494; 5,413,610; 5,507,835; 5,373,621; 5,433,750; 3,879,767;5,376,123; 5,480,437; 3,576,133; 5,376,126; 5,496,375; 3,600,718;5,108,449; 5,507,817; 5,181,929 and 5,507,829.

Foreign patents DE 2,247,721; EP 0,308,081; GB 2,126,096; GB 2,069,338;EP 0,190,446; EP 0,066,092 and EP 0,253,941.

SUMMARY OF THE INVENTION

The present invention seeks to provide improved joint implants andmethods relating to joint implantation.

The present invention seeks to provide improved joint implants andmethods relating to joint implantation.

There is thus provided in accordance with a preferred embodiment of thepresent invention an implantable artificial socket for a joint formed bymolding of polyurethane.

There is also provided in accordance with a preferred embodiment of thepresent invention a unitary implantable artificial socket for a jointformed of a resilient material.

There is further provided in accordance with a preferred embodiment ofthe present invention an implantable artificial socket for a joint andincluding a one-piece resilient element which is snap-fit engageablewith a bone and which defines a wear resistant articulation surface.

There is also provided in accordance with another preferred embodimentof the present invention a manufacturing method for an implantableartificial socket for a joint including forming the socket by molding ofpolyurethane.

Further in accordance with a preferred embodiment of the presentinvention the implantable artificial socket for a joint is generally ofuniform thickness.

Typically, the implantable artificial socket is symmetric about an axisof rotation.

Preferably, the implantable artificial socket includes a hemisphericalconcave inner articulation surface.

Preferably, the hemispherical concave inner articulation surface has abeveled edge.

Still further in accordance with a preferred embodiment of the presentinvention the implantable artificial socket for a joint includes agenerally hemispherical outer bone engagement surface.

Additionally in accordance with a preferred embodiment of the presentinvention the generally hemispherical outer bone engagement surface hasformed thereon, at a location between an apex and a rim thereof, agenerally annular outwardly extending protrusion.

Further in accordance with a preferred embodiment of the presentinvention the generally annular outwardly extending protrusion defines agenerally annular undercut.

Typically, the generally annular outwardly extending protrusion is agenerally peripheral protrusion.

Further in accordance with a preferred embodiment of the presentinvention the generally annular outwardly extending protrusion isarranged for snap-fit engagement with a corresponding groove formed byreaming of a bone.

Still further in accordance with a preferred embodiment of the presentinvention the generally annular outwardly extending protrusion has across-sectional configuration, which is characterized in that anunderlying surface portion thereof, at an undercut, defines a slopewhich is sharper than a corresponding slope of an overlying surfaceportion thereof.

Additionally in accordance with a preferred embodiment of the presentinvention the generally hemispherical outer bone engagement surface hasformed thereon, at a location between an apex and a rim thereof, agenerally annular outwardly extending array of discrete protrusions.

Preferably, the generally annular outwardly extending array of discreteprotrusions defines a generally annular array of undercuts.

Further in accordance with a preferred embodiment of the presentinvention the generally annular outwardly extending array of discreteprotrusions defines a generally peripheral array of protrusions.

Still further in accordance with a preferred embodiment of the presentinvention the generally annular outwardly extending array of discreteprotrusions is arranged for snap-fit engagement with correspondinggrooves formed in a bone.

Preferably, each protrusion within the array of protrusions has across-sectional configuration, which is characterized in that anunderlying surface portion of the protrusion, at an undercut, defines aslope, which is sharper than a corresponding slope of an overlyingsurface portion of the protrusion.

Typically, each protrusion within the array of protrusions has agenerally button-like configuration, which is symmetric about an axisand includes a body portion and an enlarged head portion.

Additionally or alternatively, protrusion within the array ofprotrusions is generally characterized in that an underlying surfaceportion of the protrusion defines a peripheral undercut with respect tothe axis.

Further in accordance with a preferred embodiment of the presentinvention the generally hemispherical outer bone engagement surface hasformed thereon, at a location between an apex and a rim thereof, agenerally annular inwardly extending recess.

Still further in accordance with a preferred embodiment of the presentinvention the generally annular inwardly extending recess defines agenerally annular undercut.

Typically, the generally annular inwardly extending recess is agenerally peripheral recess.

Additionally in accordance with a preferred embodiment of the presentinvention the generally annular inwardly extending recess is arrangedfor snap-fit engagement with a corresponding protrusion formed in abone.

Moreover in accordance with a preferred embodiment of the presentinvention the generally annular inwardly extending recess has across-sectional configuration which is characterized in that anunderlying surface portion thereof, at an undercut, defines a slope,which is sharper than a corresponding slope of an overlying surfaceportion thereof.

Further in accordance with a preferred embodiment of the presentinvention the generally hemispherical outer bone engagement surface hasformed thereon, at a location between an apex and a rim thereof, agenerally annular inwardly extending array of discrete recesses.

Still further in accordance with a preferred embodiment of the presentinvention the generally annular inwardly extending array of discreterecesses defines a generally annular array of undercuts.

Additionally in accordance with a preferred embodiment of the presentinvention the generally annular inwardly extending array of discreterecesses defines a generally peripheral array of recesses.

Typically, the generally annular inwardly extending array of discreterecesses is arranged for snap-fit engagement with correspondingprotrusions formed in a bone.

Further in accordance with a preferred embodiment of the presentinvention each recess of the array of recesses has a cross-sectionalconfiguration, which is characterized in that an underlying surfaceportion of the recess, at an undercut, defines a slope which is sharperthan a corresponding slope of an overlying surface portion of therecess.

Additionally in accordance with a preferred embodiment of the presentinvention each recess of the array of recesses has a generallybutton-like configuration, which is symmetric about an axis and includesa body portion and an enlarged head portion.

Still further in accordance with a preferred embodiment of the presentinvention each recess of the array of recesses is generallycharacterized in that an underlying surface portion of the recessdefines a peripheral undercut with respect to the axis.

There is also provided in accordance with a preferred embodiment of thepresent invention an implantable artificial femoral head resurfacingelement for a joint formed by molding of polyurethane.

There is further provided in accordance with yet another preferredembodiment of the present invention a manufacturing method for animplantable artificial humeral head resurfacing element for a joint. Themethod includes forming the resurfacing element by molding ofpolyurethane.

Further in accordance with a preferred embodiment of the presentinvention the implantable artificial femoral head resurfacing elementfor a joint is generally of uniform thickness other than at its apex,which is thickened.

Typically, the implantable artificial femoral head resurfacing elementfor a joint is symmetric about an axis of rotation.

Still further in accordance with a preferred embodiment of the presentinvention the implantable artificial femoral head resurfacing elementfor a joint includes a hemispherical outer articulation surface.

Typically, the hemispherical outer articulation surface has a bevelededge.

Further in accordance with a preferred embodiment of the presentinvention the implantable artificial femoral head resurfacing elementfor a joint includes a generally hemispherical inner bone engagementsurface.

Typically, the generally hemispherical inner bone engagement surface hasformed thereon, at a location between an apex and a rim thereof, agenerally annular inwardly extending protrusion.

Further in accordance with a preferred embodiment of the presentinvention the generally annular inwardly extending protrusion defines agenerally annular undercut.

Still further in accordance with a preferred embodiment of the presentinvention the generally annular inwardly extending protrusion is agenerally peripheral protrusion.

Additionally in accordance with a preferred embodiment of the presentinvention the generally annular inwardly extending protrusion isarranged for snap-fit engagement with a corresponding groove formed byreaming of a bone.

Typically, the generally annular inwardly extending protrusion has across-sectional configuration, which is characterized in that anunderlying surface portion thereof at an undercut defines a slope, whichis sharper than a corresponding slope of an overlying surface portionthereof.

Further in accordance with a preferred embodiment of the presentinvention the generally hemispherical inner bone engagement surface hasformed thereon, at a location between an apex and a rim thereof, agenerally annular inwardly extending array of discrete protrusions.

Additionally in accordance with a preferred embodiment of the presentinvention the generally annular inwardly extending array of discreteprotrusions defines a generally annular array of undercuts.

Additionally or alternatively, the generally annular inwardly extendingarray of discrete protrusions defines a generally peripheral array ofprotrusions.

Typically, the generally annular inwardly extending array of discreteprotrusions is arranged for snap-fit engagement with correspondinggrooves formed in a bone.

Further in accordance with a preferred embodiment of the presentinvention each protrusion within the array of protrusions has across-sectional configuration, which is characterized in that anunderlying surface portion of the protrusion, at an undercut, defines aslope which is sharper than a corresponding slope of an overlyingsurface portion of the protrusion.

Typically, each protrusion within the array of protrusions has agenerally button-like configuration, which is symmetric about an axisand includes a body portion and an enlarged head portion.

Typically, each protrusion within the array of protrusions is generallycharacterized in that an underlying surface portion of the protrusiondefines a peripheral undercut with respect to the axis.

Further in accordance with a preferred embodiment of the presentinvention the generally hemispherical inner bone engagement surface hasformed thereon, at a location between an apex and a rim thereof, agenerally annular outwardly extending recess.

Still further in accordance with a preferred embodiment of the presentinvention the generally annular outwardly extending recess defines agenerally annular undercut.

Typically, the generally annular outwardly extending recess is agenerally peripheral recess.

Additionally in accordance with a preferred embodiment of the presentinvention the generally annular outwardly extending recess is arrangedfor snap-fit engagement with a corresponding protrusion formed in abone.

Further in accordance with a preferred embodiment of the presentinvention the generally annular outwardly extending recess has across-sectional configuration, which is characterized in that anunderlying surface portion thereof at an undercut defines a slope, whichis sharper than a corresponding slope of an overlying surface portionthereof.

Still further in accordance with a preferred embodiment of the presentinvention the generally hemispherical inner bone engagement surface hasformed thereon, at a location between an apex and a rim thereof, agenerally annular outwardly extending array of discrete recesses.

Typically, the generally annular outwardly extending array of discreterecesses defines a generally annular array of undercuts.

Additionally or alternatively, the generally annular outwardly extendingarray of discrete recesses defines a generally peripheral array ofrecesses.

Further in accordance with a preferred embodiment of the presentinvention the generally annular outwardly extending array of discreterecesses is arranged for snap-fit engagement with correspondingprotrusions formed in a bone.

Still further in accordance with a preferred embodiment of the presentinvention each recess in the array of recesses has a cross-sectionalconfiguration, which is characterized in that an underlying surfaceportion of the recess, at an undercut, defines a slope which is sharperthan a corresponding slope of an overlying surface portion of therecess.

Typically, each recess within the array of recesses has a generallybutton-like configuration, which is symmetric about an axis and includesa body portion and an enlarged head portion.

Preferably, each recess within the array of recesses is generallycharacterized in that an underlying surface portion of the recessdefines a peripheral undercut with respect to the axis.

Further in accordance with a preferred embodiment of the presentinvention the implantable artificial socket is typically snap-fittedinto a suitably machined natural acetabulum of a patient and having anartificial femoral head mounted onto a conventional femoral stem andarranged for articulation with an articulation surface of the socket.

Still further in accordance with a preferred embodiment of the presentinvention the implantable artificial socket is typically snap-fittedinto a suitably machined natural acetabulum of a patient and having anatural femoral head arranged for articulation with an articulationsurface of the socket.

Additionally in accordance with a preferred embodiment of the presentinvention the size and configuration of an articulation surface of thesocket is identical to that of the natural acetabulum socket of thepatient, in order that a natural femoral head may articulate therewithwith desired dimensional clearances and without requiring machining ofthe femoral head.

Further in accordance with a preferred embodiment of the presentinvention the implantable artificial socket is typically snap-fittedinto a suitably machined natural acetabulum of a patient and having anatural femoral head having an implantable artificial femoral headresurfacing element and is preferably snap-fit mounted thereon arrangedfor articulation of an articulation surface thereof with an articulationsurface of the socket.

Typically, the implantable artificial femoral head resurfacing elementis snap-fit mounted onto a natural femoral head and arranged forarticulation of an articulation surface thereof with a naturalarticulation surface of a natural acetabulum.

Further in accordance with a preferred embodiment of the presentinvention the implantable artificial femoral head resurfacing element issnap-fit mounted onto a natural femoral head and arranged forarticulation of an articulation surface thereof with a naturalacetabulum socket of a patient, wherein the size and configuration of anarticulation surface of the artificial femoral head resurfacing elementis identical to that of the natural acetabulum socket of the patient, inorder that the natural femoral head onto which artificial femoral headresurfacing element is mounted may articulate therewith with desireddimensional clearances and without requiring machining of the naturalacetabulum.

Preferably, the implantable artificial socket for a joint includes aspherical concave inner articulation surface.

Typically, the spherical concave inner articulation surface has abeveled edge.

Further in accordance with a preferred embodiment of the presentinvention the implantable artificial socket for a joint includes anouter bone engagement surface.

Preferably, the outer bone engagement surface has multiple protrusionsformed thereon.

Further in accordance with a preferred embodiment of the presentinvention the multiple protrusions include inner and outer protrusions.

Preferably, the multiple protrusions include undercuts.

Still further in accordance with a preferred embodiment of the presentinvention the multiple protrusions are arranged for snap-fit engagementwith a corresponding groove formed in a bone.

Additionally in accordance with a preferred embodiment of the presentinvention the multiple protrusions include a cross-sectionalconfiguration which is characterized in that an underlying surfaceportion thereof at an undercut defines a slope, which is sharper than acorresponding slope of an overlying surface portion thereof.

Typically, the multiple protrusions include an array of outwardlyextending discrete protrusions.

Further in accordance with a preferred embodiment of the presentinvention the array of discrete protrusions defines an array ofundercuts.

Typically, the array of discrete protrusions includes a generallyperipheral array of protrusions.

Still further in accordance with a preferred embodiment of the presentinvention the array of discrete protrusions is arranged for snap-fitengagement with corresponding grooves formed in a bone.

Additionally in accordance with a preferred embodiment of the presentinvention each protrusion within the array of protrusions has across-sectional configuration, which is characterized in that anunderlying surface portion of the protrusion, at an undercut, defines aslope which is sharper than a corresponding slope of all overlyingsurface portion of the protrusion.

Typically, each protrusion within the array of protrusions has agenerally button-like configuration, which is symmetric about an axisand includes a body portion and an enlarged head portion.

Further in accordance with a preferred embodiment of the presentinvention the protrusion within the array of protrusions is generallycharacterized in that an underlying surface portion of the protrusiondefines a peripheral undercut with respect to the axis.

Still further in accordance with a preferred embodiment of the presentinvention the outer bone engagement surface has multiple recesses formedthereon.

Typically, the multiple recesses include undercuts.

Further in accordance with a preferred embodiment of the presentinvention the multiple recesses include an inner recess and outerprotrusions.

Typically, the multiple recesses are arranged for snap-fit engagementwith corresponding protrusions formed in a bone.

Further in accordance with a preferred embodiment of the presentinvention the multiple recesses has a cross-sectional configurationwhich is characterized in that an underlying surface portion thereof atan undercut defines a slope which is sharper than a corresponding slopeof an overlying surface portion thereof.

Additionally in accordance with a preferred embodiment of the presentinvention the outer bone engagement surface has formed thereon aninwardly extending array of discrete recesses.

Typically, the array of discrete recesses includes an array ofundercuts.

Further in accordance with a preferred embodiment of the presentinvention the array of discrete recesses includes a generally peripheralarray of recesses.

Still further in accordance with a preferred embodiment of the presentinvention the array of discrete recesses is arranged for snap-fitengagement with corresponding protrusions formed in a bone.

Additionally in accordance with a preferred embodiment of the presentinvention each recess within the array of recesses has a cross-sectionalconfiguration which is characterized in that an underlying surfaceportion of each recess, at an undercut, defines a slope which is sharperthan a corresponding slope of an overlying surface portion of therecess.

Typically, each recess within the array of recesses has a generallybutton-like configuration, which is symmetric about an axis and includesa body portion and an enlarged head portion.

Further in accordance with a preferred embodiment of the presentinvention each recess within the array of recesses is generallycharacterized in that an underlying surface portion of the recessdefines a peripheral undercut with respect to the axis.

There is further provided in accordance with a preferred embodiment ofthe present invention an implantable artificial humeral head resurfacingelement for a joint Formed by molding of polyurethane.

There is further provided in accordance with yet another preferredembodiment of the present invention a manufacturing method for animplantable artificial femoral head resurfacing, element for a joint.The method includes forming the resurfacing element by molding ofpolyurethane.

Further in accordance with a preferred embodiment of the presentinvention the implantable artificial humeral head resurfacing elementfor a joint is generally of uniform thickness other than at its apex,which is thickened.

Still further in accordance with a preferred embodiment of the presentinvention the implantable artificial humeral head resurfacing elementfor a joint is symmetric about an axis of rotation.

Additionally in accordance with a preferred embodiment of the presentinvention the implantable artificial humeral head resurfacing elementfor a joint includes a convex spherical outer articulation surface.

Typically, the convex spherical outer articulation surface has a bevelededge.

Further in accordance with a preferred embodiment of the presentinvention the implantable artificial humeral head resurfacing elementfor a joint includes a generally convex spherical inner bone engagementsurface.

Typically, the generally convex spherical inner bone engagement surfacehas formed thereon, at a location between an apex and a rim thereof, agenerally annular inwardly extending protrusion.

Additionally in accordance with a preferred embodiment of the presentinvention the generally annular inwardly extending protrusion defines agenerally annular undercut.

Preferably, the generally annular inwardly extending protrusion is agenerally peripheral protrusion.

Further in accordance with a preferred embodiment of the presentinvention the generally annular inwardly extending protrusion isarranged for snap-fit engagement with a corresponding groove formed byreaming of a bone.

Further in accordance with a preferred embodiment of the presentinvention in generally annular inwardly extending protrusion has across-sectional configuration, which is characterized in that anunderlying surface portion thereof at an undercut defines a slope, whichis sharper than a corresponding slope of an overlying surface portionthereof.

Further in accordance with a preferred embodiment of the presentinvention the generally convex spherical inner bone engagement surfacehas formed thereon, at a location between an apex and a rim thereof, agenerally annular inwardly extending array of discrete protrusions.

Preferably, the generally annular inwardly extending array of discreteprotrusions defines a generally annular array of undercuts.

Additionally or alternatively, the generally annular inwardly extendingarray of discrete protrusions includes a generally peripheral array ofprotrusions.

Still further in accordance with a preferred embodiment of the presentinvention the generally annular inwardly extending array of discreteprotrusions is arranged for snap-fit engagement with correspondinggrooves formed in a bone.

Further in accordance with a preferred embodiment of the presentinvention each protrusion within the array of protrusions has across-sectional configuration, which is characterized in that anunderlying surface portion of the protrusion, at an undercut, defines aslope which is sharper than a corresponding slope of an overlyingsurface portion of the protrusion.

Typically, each protrusion within the array of protrusions has agenerally button-like configuration, which is symmetric about an axisand includes a body portion and an enlarged head portion.

Still further in accordance with a preferred embodiment of the presentinvention each protrusion within the array of protrusions is generallycharacterized in that an underlying surface portion of the protrusiondefines a peripheral undercut with respect to the axis.

Additionally in accordance with a preferred embodiment of the presentinvention the generally convex spherical inner bone engagement surfaceincludes thereon, at a location between an apex and a rim thereof, agenerally annular outwardly extending recess.

Further in accordance with a preferred embodiment of the presentinvention the generally annular outwardly extending recess defines agenerally annular undercut.

Typically, the generally annular outwardly extending recess is agenerally peripheral recess.

Further in accordance with a preferred embodiment of the presentinvention the generally annular outwardly extending recess is arrangedfor snap-fit engagement with a corresponding protrusion formed in abone.

Still further in accordance with a preferred embodiment of the presentinvention the generally annular outwardly extending recess has across-sectional configuration, which is characterized in that anunderlying surface portion thereof at an undercut defines a slope, whichis sharper than a corresponding slope of an overlying surface portionthereof.

Further in accordance with a preferred embodiment of the presentinvention the generally convex spherical inner bone engagement surfacehas formed thereon, at a location between an apex and a rim thereof, agenerally annular outwardly extending array of discrete recesses.

Preferably, the generally annular outwardly extending array of discreterecesses defines a generally annular array of undercuts.

Typically, the generally annular outwardly extending array of discreterecesses defines a generally peripheral array of recesses.

Additionally in accordance with a preferred embodiment of the presentinvention the generally annular outwardly extending array of discreterecesses is arranged for snap-fit engagement with correspondingprotrusions formed in a bone.

Typically, each recess within the array of recesses has across-sectional configuration, which is characterized in that anunderlying surface portion of each recess, at an undercut, defines aslope, which is sharper than a corresponding slope of an overlyingsurface portion of the recess.

Further in accordance with a preferred embodiment of the presentinvention each recess within the array of recesses has a generallybutton-like configuration, which is symmetric about an axis and includesa body portion and an engaged head portion.

Still further in accordance with a preferred embodiment of the presentinvention each recess within the array of recesses is generallycharacterized in that an underlying surface portion of each recessdefines a peripheral undercut with respect to the axis.

Additionally in accordance with a preferred embodiment of the presentinvention the implantable artificial socket according is snap-fittedinto a suitably machined natural glenoid of a patient and having anartificial humeral head mounted onto a conventional humeral stem andarranged for articulation with an articulation surface of the socket.

Still further in accordance with a preferred embodiment of the presentinvention the implantable artificial socket is snap-fitted into asuitably machined natural glenoid of a patient and having a naturalhumeral head arranged for articulation with an articulation surface ofthe socket.

Typically, the size and configuration of an articulation surface of thesocket is identical to that of the natural glenoid socket of thepatient, in order that a natural humeral head may articulate therewithwith desired dimensional clearances and without requiring machining ofthe humeral head.

Additionally in accordance with a preferred embodiment of the presentinvention the implantable artificial socket is snap-fitted into asuitably machined natural glenoid of a patient and having a naturalhumeral head having an implantable artificial humeral head resurfacingelement and is typically snap-fit mounted thereon arranged forarticulation of an articulation surface thereof with an articulationsurface of the socket.

Further in accordance with a preferred embodiment of the presentinvention the implantable artificial humeral head resurfacing element issnap-fit mounted onto a natural humeral head and arranged forarticulation of an articulation surface thereof with a naturalarticulation surface of a natural glenoid.

Still further in accordance with a preferred embodiment of the presentinvention the implantable artificial humeral head resurfacing element issnap-fit mounted onto a natural humeral head and arranged forarticulation of an articulation surface hereof with a natural glenoidsocket of a patient, wherein the size and configuration of anarticulation surface of the artificial humeral head resurfacing elementis identical to that of the natural glenoid socket of the patient, inorder that the natural humeral head onto which artificial humeral headresurfacing element is mounted may articulate therewith with desireddimensional clearances and without requiring machining of the naturalglenoid.

Preferably, the articulation portion is formed with a highly resilienthollow peripheral rim arranged for snap-fit engagement with acorresponding peripheral socket formed in a surface of the boneengagement portion, opposite to the bone engagement surface.

Additionally in accordance with a preferred embodiment of the presentinvention the articulation portion is formed with a support protrusion,defining an under-cut and arranged for resilient snap-fit lockingengagement with a corresponding groove formed in the bone engagementportion.

Further in accordance with a preferred embodiment of the presentinvention the articulation surface has formed therein a plurality ofthoroughgoing apertures and side openings, which allow synovial fluid topass therethrough for lubrication of the articulation surface.

Still further in accordance with a preferred embodiment of the presentinvention the implantable artificial socket for a joint is mounted ontoa tibia and arranged such that application of force to the joint causesthe articulation portion to be resiliently displaced toward the boneengagement portion, thus causing synovial fluid, located between thearticulation portion and the bone engagement portion, to be forcedthrough apertures and openings so as to lie on and over the articulationsurface and to provide enhanced lubrication for the articulation of anarticulation surface of a femur with the articulation surface.

Typically, the application of force causes the movement of thearticulation portion by resilient buckling of at least one protrusionand compression of a resilient rim and release of the force causesmovement of articulation portion, accompanied by resilient return of theprotrusion to its unstressed orientation and decompression of theresilient rim, wherein the application of force does not causesignificant deformation of the geometry of the articulation surface.

There is also provided in accordance with another preferred embodimentof the present invention a method for implanting an implantableartificial socket. The method for implanting an implantable artificialsocket includes providing an implantable artificial socket, suitablymachining a natural acetabulum of a patient to fit the implantableartificial socket, snap-fitting the implantable artificial socket ontothe natural acetabulum, mounting an artificial femoral head onto aconventional femoral stem and arranging the femoral head forarticulation with an articulation surface of the implantable artificialsocket.

There is further provided in accordance with yet another preferredembodiment of the present invention a method for implanting animplantable artificial socket. The method includes providing animplantable artificial socket, suitably machining a natural acetabulumof a patient to fit the implantable artificial socket, snap-fitting theimplantable artificial socket onto the natural acetabulum and arranginga natural femoral head for articulation with an articulation surface ofthe implantable artificial socket.

Further in accordance with a preferred embodiment of the presentinvention the method for implanting an implantable artificial socketalso includes matching the size and configuration of an articulationsurface of the socket to that of the natural acetabulum socket of thepatient and arranging a natural femoral head for articulation therewith,the matching providing desired dimensional clearances without requiringmachining of the femoral head.

There is provided in accordance with still a further embodiment of thepresent invention a method for implanting an implantable artificialsocket. The method includes providing an implantable artificial socket,suitably machining a natural acetabulum of a patient to fit theimplantable artificial socket, snap-fitting the implantable artificialsocket onto the natural acetabulum, snap-fit mounting an implantableartificial femoral head resurfacing element onto a natural femoral headand arranging an articulation surface of the femoral head forarticulation with an articulation surface of the implantable artificialsocket.

There is also provided in accordance with another preferred embodimentof the present invention a method for implanting an implantableartificial femoral head resurfacing element. The method includesproviding an implantable artificial femoral head resurfacing element,snap-fit mounting the artificial femoral head resurfacing element ontoat natural femoral head and arranging an articulation surface of theartificial femoral head resurfacing element for articulation with anatural articulation surface of a natural acetabulum.

Still further in accordance with a preferred embodiment of the presentinvention the method also includes matching the size and configurationof an articulation surface of the artificial femoral head resurfacingelement to that of the natural acetabulum socket of the patient, thematching providing for the natural femoral head onto which theartificial femoral head resurfacing element is mounted to articulatewith the natural acetabulum socket with desired dimensional clearanceswithout requiring machining of the natural acetabulum.

There is also provided in accordance with a preferred embodiment of thepresent invention a method for implanting an implantable artificialsocket, which includes providing an implantable artificial socket,suitably machining a natural glenoid of a patient to fit the implantableartificial socket, snap-fitting the implantable artificial socket intothe natural glenoid, mounting an artificial humeral head onto aconventional humeral stem and arranging the humeral head forarticulation with an articulation surface of the implantable artificialsocket.

There is further provided in accordance with another preferredembodiment of the present invention a method for implanting animplantable artificial socket, which includes providing an implantableartificial socket, suitably machining a natural glenoid of a patient tofit the implantable artificial socket, snap-fitting the implantableartificial socket into the natural glenoid and arranging a naturalhumeral head for articulation with an articulation surface of theimplantable artificial socket

Further in accordance with a preferred embodiment of the presentinvention the method for implanting an implantable artificial socketalso includes matching the size and configuration of an articulationsurface of the socket to that of the natural glenoid socket of thepatient and arranging a natural humeral head for articulation therewith,the matching providing desired dimensional clearances without requiringmachining of the humeral head.

There is also provided in accordance with a further preferred embodimentof the present invention a method for implanting an implantableartificial socket. The method includes providing an implantableartificial socket, suitably machining a natural glenoid of a patient tofit the implantable artificial socket, snap-fitting the implantableartificial socket onto the natural glenoid, snap-fit mounting animplantable artificial humeral head resurfacing element onto a naturalhumeral head and arranging an articulation surface of the humeral headfor articulation with an articulation surface of the implantableartificial socket.

There is further provided in accordance with yet another preferredembodiment of the present invention a method for implanting animplantable artificial humeral head resurfacing element. The methodincludes providing an implantable artificial humeral head resurfacingelement, snap-fit mounting the artificial humeral head resurfacingelement onto a natural humeral head and arranging an articulationsurface of the artificial humeral head resurfacing element forarticulation with a natural articulation surface of a natural glenoid.

Further in accordance with a preferred embodiment of the presentinvention the method for implanting an implantable artificial humeralhead resurfacing element also includes matching the size andconfiguration of an articulation surface of the artificial humeral headresurfacing element to that of the natural glenoid socket of thepatient, the matching providing for the natural humeral head onto whichthe artificial humeral head resurfacing element is mounted to articulatewith the natural glenoid socket with desired dimensional clearanceswithout requiring machining of the natural glenoid.

Further in accordance with a preferred embodiment of the presentinvention the implantable artificial femoral resurfacing element for ajoint defines an articulation portion having a convex outer articulationsurface and a bone engagement portion having a bone engagement surface.

Still further in accordance with a preferred embodiment of the presentinvention the articulation portion of the artificial socket for a jointis formed with a highly resilient hollow peripheral rim arranged forsnap-fit engagement with a corresponding peripheral femoral resurfacingelement formed in a surface of the bone engagement portion, opposite tothe bone engagement surface.

Additionally in accordance with a preferred embodiment of the presentinvention the articulation portion is formed with a support protrusion,defining an undercut and arranged for resilient snap-fit lockingengagement with a corresponding groove formed in the bone engagementportion.

Typically, the articulation surface has formed therein a plurality ofthoroughgoing apertures and side openings, which allow synovial fluid topass therethrough for lubrication of the articulation surface.

Further in accordance with a preferred embodiment of the presentinvention the implantable artificial femoral resurfacing element for ajoint is mounted onto a femur and arranged such that application offorce to the joint causes the articulation portion to be resilientlydisplaced toward the bone engagement portion, thus causing synovialfluid, located between the articulation portion and the bone engagementportion to be forced through apertures and openings so as to lie on andover articulation surface and to provide enhanced lubrication for thearticulation of an articulation surface of a femur with the articulationsurface.

Typically, the application of force causes the movement of thearticulation portion by resilient buckling of at least one protrusionand compression of a resilient rim and release of the force causesmovement of articulation portion, accompanied by resilient return of theprotrusion to its unstressed orientation and decompression of theresilient rim, wherein the application of force does not causesignificant deformation of the geometry of the articulation surface.

Further in accordance with a preferred embodiment of the presentinvention the implantable artificial socket is in articulationengagement with an implantable artificial femoral resurfacing element.

There is further provided in accordance with a preferred embodiment ofthe present invention a groove reaming tool including a shaft, a handle,fixedly coupled to the shaft, an outwardly extendible recess engagementelement, which is also rotatably and slidably mounted with respect tothe shaft and an elongate grip, rotatably and slidably mounted over theshaft and axially engaging the outwardly extendible recess engagementelement.

Further in accordance with a preferred embodiment of the presentinvention the outwardly extendible recess engagement element is anintegrally formed element and includes a generally hollow cylindricalportion formed with a plurality of axially extending slots, which extendfrom a location spaced from a top edge of the cylindrical portiontowards and through a generally radially outwardly extending disk-likeportion.

Still further in accordance with a preferred embodiment of the presentinvention the disk-like portion includes a plurality of azimuthallyseparated segments, each of which defines a continuation of acorresponding azimuthally separated segment of the cylindrical portion.

Preferably, the disk-like portion has an outer edge which is formed witha high friction engagement surface.

Further in accordance with a preferred embodiment of the presentinvention the disk-like portion is formed with a central generallyconical recess on an underside surface thereof.

Preferably, the groove reaming tool also includes a generally solid,centrally apertured conical element, rotatably mounted onto the shaftsuch that a conical surface thereof is adapted to operative engage theconical recess in a manner that such engagement produces radiallyoutward displacement of the segments of the disk-like portion.

Further in accordance with a preferred embodiment of the presentinvention the groove reaming tool further includes a retainer elementwhich is rotatably mounted with respect to the shaft and overlies thedisk-like portion.

Additionally in accordance with a preferred embodiment of the presentinvention the retainer element includes depending plates which engageinterstices between the segments.

Further in accordance with a preferred embodiment of the presentinvention groove reaming tool also includes a groove cutter assembly.

Preferably, the groove cutter assembly includes a groove cutter mountingelement, fixedly mounted to the shaft for rotation together therewith inresponse to rotation of the handle.

Further in accordance with a preferred embodiment of the presentinvention the groove cutter mounting element underlies conical elementand is separated therefrom by a washer, in order to enable the groovecutter mounting element to easily rotate with respect to the conicalelement.

Still further in accordance with a preferred embodiment of the presentinvention the groove reaming tool further includes an end element,rotatably mounted onto an end of the shaft, underlying the groove cuttermounting element such that the groove cutter mounting element isrotatable with respect thereto.

Typically, the end element is formed with a high friction engagementsurface on the underside thereof.

Further in accordance with a preferred embodiment of the presentinvention the groove cutter mounting element is a generally hollowhemispherical element having a central hub which defines a non-circularthoroughgoing aperture for receiving an end of the shaft, a radiallyinward extending recess is formed in an outer facing wall of the hub anda corresponding (generally elongate aperture is formed in a wall of thegroove cutter mounting element opposite the recess and extendsazimuthally beyond the recess.

Additionally in accordance with a preferred embodiment of the presentinvention the groove reaming tool also includes a plurality of cutterelements, removably retained in the groove cutter mounting element.

Preferably, the cutter elements have similar configurations and have atleast one differing dimension.

Further in accordance with a preferred embodiment of the presentinvention each cutter element is formed of a flat piece of metal andincludes a hook portion, defining an undercut, a central portion and acutting portion, which defines a curved cutting edge.

Preferably, the cutting portion defines, inwardly of the curved cuttingedge, an aperture having a beveled peripheral edge.

Further in accordance with a preferred embodiment of the presentinvention the cutter elements are arranged such that their hook portionsengage the recess and the cutting portions extend outwardly through theaperture.

Still further in accordance with a preferred embodiment of the presentinvention the cutter elements are arranged to provide a stepped increasein the extent that the cutting portions extend outwardly, in thedirection of operational rotation of the tool.

Additionally in accordance with a preferred embodiment of the presentinvention the tool has first and second operative orientations, thefirst operative orientation being a non-engagement orientation, when thegrip is not pushed along the shaft towards the groove cutter mountingelement and the outwardly extendible recess engagement element is notsubject to axial force and thus no axial force is applied between therecess on the underside surface thereof and the conical element.

Preferably, in the second operative orientation is bone recessengagement orientation wherein the grip is pushed along the shafttowards the groove cutter mounting element and engages the outwardlyextendible recess engagement element, forcing the recess on theunderside surface thereof axially against the conical element andcausing radically outward displacement of the segments of the disk-likeportion.

Further in accordance with a preferred embodiment of the presentinvention a method of groove reaming of an acetabulum including engaginga groove reaming tool with an acetabulum which has been at leastpartially spherically reamed by aligning the cutting portions of thecutting elements with an acetabulum notch and arranging the shaft alongan axis which is approximately coaxial with an axis of symmetry of theat least partially spherically reamed acetabulum.

Still further in accordance with a preferred embodiment of the presentinvention the method also includes applying an axial force on thehandle, thereby causing the high friction engagement surface of the endelement to frictionally engage the at least partially spherically reamedacetabulum.

Additionally in accordance with a preferred embodiment of the presentinvention the method further includes applying an axial force on thegrip, causing the grip to engage the outwardly extendible recessengagement element and to force the recess on the underside surfacethereof axially against the conical element, thereby causing radiallyoutward displacement of the segments into frictional engagement with theat least partially spherically reamed acetabulum.

Further in accordance with a preferred embodiment of the presentinvention the method also includes rotating the handle through anapproximately 180 degree rotation thereby producing correspondingrotation of the groove cutter mounting element and the cutter elementsand thereby producing an approximately 180 degree groove in the at leastpartially spherically reamed acetabulum.

Additionally in accordance with a preferred embodiment of the presentinvention the method includes rotating the handle through a furtherapproximately 180 degree rotation thereby producing correspondingrotation of the groove cutter mounting element and the cutter elementsand thereby producing an approximately 180 degree groove in the at leastpartially spherically reamed acetabulum.

There is further provided in accordance with a preferred embodiment ofthe present invention a method for implanting an artificial acetabulumsocket in a hip joint, which includes at least partially reaming of anatural acetabulum to provide a snap-fit configured natural acetabulumand resiliently bending an artificial acetabulum socket, so as toprovide a bent acetabulum socket having a reduced minimumcross-sectional area, inserting the bent acetabulum socket having areduced minimum cross-sectional area into the vicinity of the hip jointby a minimally invasive surgical technique and snap fitting theartificial acetabulum socket in the snap-fit configured naturalacetabulum.

There is also provided in accordance with a preferred embodiment of thepresent invention a method for implanting an artificial acetabulumsocket in a hip joint. The method includes at least partially reaming ofa natural acetabulum to provide a snap-fit configured natural acetabulumand inserting a unitary resilient acetabulum socket into the vicinity ofthe hip joint and snap fitting the artificial acetabulum socket in thesnap-fit configured natural acetabulum.

Further in accordance with a preferred embodiment of the presentinvention the snap-fit configured natural acetabulum includes agenerally spherical portion and a generally cylindrical portion.

Still further in accordance with a preferred embodiment of the presentinvention the snap-fit configured natural acetabulum defines a recessedrim.

Additionally in accordance with a preferred embodiment of the presentinvention the snap-fit configured natural acetabulum is naturally formedwith a recess which extends deeper than the remainder of the generallyspherical surface.

Preferably, the snap fitting the artificial acetabulum socket in thesnap-fit configured natural acetabulum includes gently positioning theartificial acetabulum socket into a position for snap-fit engagementwith the reamed acetabulum.

Further in accordance with a preferred embodiment of the presentinvention that during the gently positioning an outwardly extendingprotrusion of the artificial acetabulum socket lies in touching,generally non-compressive engagement with an annular portion of agenerally spherical inner concave machined surface the acetabulum, theannular portion lying, above a groove, formed in the generally sphericalinner concave surface, which is designed to receive the protrusion.

Still further in accordance with a preferred embodiment of the presentinvention that during the gently positioning the engagement of theprotrusion with the annular portion causes the implantable artificialacetabulum socket to rest at a position wherein an outer edge thereoflies above a corresponding outer edge of the acetabulum.

Further in accordance with a preferred embodiment of the presentinvention that during the gently positioning, substantially no stress isapplied to the implantable artificial acetabulum socket and to theacetabulum by the engagement thereof.

Additionally in accordance with a preferred embodiment of the presentinvention the method also includes, following the gently positioning,gently engaging the artificial acetabulum socket at locations on aninner concave surface thereof and pressing thereon in a directiongenerally along an axis of symmetry of the snap-fit configured naturalacetabulum, thereby causing displacement of the artificial acetabulumsocket, which produces radially inward compression of the artificialacetabulum socket at the protrusion and thereby resulting in deformationof the artificial acetabulum socket at the protrusion and in the generalregion thereof.

Further in accordance with a preferred embodiment of the presentinvention the radially inward compression and the resulting deformationof the artificial acetabulum socket produce stresses in the acetabulumsocket and causes forces to be applied to the acetabulum, producingcompression stresses and strains therein.

Additionally in accordance with a preferred embodiment of the presentinvention the displacement of the artificial acetabulum socket reducesthe separation between the planes of the outer edge of the implantableartificial acetabulum socket and the outer edge of the acetabulum.

Still further in accordance with a preferred embodiment of the presentinvention the method includes, following the gently engaging, pressingfurther on the artificial acetabulum socket at locations on an innerconcave surface thereof, thereby causing further displacement of theartificial acetabulum socket producing sliding pressure engagementbetween an underlying surface portion of the protrusion at the undercutand a radially outward extending surface portion of the groove, whereinresiliency of the artificial acetabulum socket causes radially outwarddisplacement of the protrusion and corresponding radially outwarddecompression of the artificial acetabulum socket, resulting in reducedand changed stress patterns in both the artificial acetabulum socket andin the acetabulum.

Further in accordance with a preferred embodiment of the presentinvention the displacement of the artificial acetabulum socket furtherreduces the separation between the planes of the outer edge of theimplantable artificial acetabulum socket and the outer edge of theacetabulum.

Further in accordance with a preferred embodiment of the presentinvention the method further includes, following the pressing further,pressing on the artificial acetabulum socket at locations on edgesthereof, thereby causing further displacement of the artificialacetabulum socket and producing sliding snap-fit engagement between theprotrusion and the groove, wherein the resiliency of the artificialacetabulum socket causes radially outward displacement of theprotrusion, thereby generally eliminating deformation of the artificialacetabulum socket at the protrusion and in the general region thereof.

Preferably, the snap fitting provides a generally non-press fitengagement, wherein touching engagement between the artificialacetabulum socket and the acetabulum produces stresses in both theacetabulum socket and in the acetabulum which are generally small andlocalized in the region of the snap fit engagement therebetween.

Further in accordance with a preferred embodiment of the presentinvention the snap fitting produces locking of the artificial acetabulumsocket in the groove and the undercut prevents disengagement of theprotrusion from the groove.

Additionally in accordance with a preferred embodiment of the presentinvention the snap fitting provides a generally press fit engagement,wherein touching engagement between the artificial acetabulum socket andthe acetabulum produces stresses in both the acetabulum socket and inthe acetabulum which are not localized in the region of the snap fitengagement therebetween.

Further in accordance with a preferred embodiment of the presentinvention the snap fitting in a generally press fit engagement producespressure engagement between the acetabulum and a convex facing surfaceof the artificial acetabulum socket generally along the entire extentthereof.

There is also provided in accordance with a preferred embodiment of thepresent invention an artificial femoral head prosthesis for use with anatural femoral head and including a flexible bone interface elementincluding a unitary element molded of a single material and having aninner concave surface which is configured to directly contact thenatural femoral head in generally static engagement therewith and asmooth outer convex surface which is configured to be directly contactedby an acetabulum socket in moveable engagement therewith, the flexiblebone interface element being formed of material which is more flexiblethan bone material of the natural femoral head.

There is also provided in accordance with a preferred embodiment of thepresent invention an artificial femoral head prosthesis for use with anatural femoral head and including a flexible bone interface elementconfigured to be mounted onto the natural femoral head, the flexiblebone interface element including a unitary element molded of a singlematerial and having an inner concave surface which is configured todirectly contact the natural femoral head in generally static engagementtherewith, and a smooth outer convex surface which is configured to bedirectly contacted by an acetabulum socket in moveable engagementtherewith, the flexible bone interface element being formed of materialwhich is more flexible than bone material of particularly configured forretainable snap-fit engagement with a suitably machine-shaped surface ofthe natural femoral head.

There is also provided in accordance with a preferred embodiment of thepresent invention an artificial femoral head prosthesis for use with anatural femoral head and including a bone interface element configuredto be mounted onto the natural femoral head, the bone interface elementhaving an inner concave surface which is configured to directly contactthe natural femoral head in generally static engagement therewith, thebone interface element being particularly configured for retainablesnap-fit engagement with a suitably machine-shaped surface of thenatural femoral head and a press-fit acetabulum engagement element beingparticularly configured for retainable press-fit engagement with thebone interface element and having a smooth outer convex surface which isconfigured to be directly contacted by an acetabulum socket in moveableengagement therewith.

There is also provided in accordance with yet another preferredembodiment of the present invention an artificial femoral headprosthesis for use with a natural femoral head and including a boneinterface element configured to be mounted onto the natural femoralhead, the bone interface element having an inner concave surface whichis configured to directly contact the natural femoral head in generallystatic engagement therewith, the bone interface element beingparticularly configured for retainable snap-fit engagement with asuitably machine-shaped surface of the natural femoral head and asnap-fit acetabulum engagement element being particularly configured forretainable snap-fit engagement with the bone interface element andhaving a smooth outer convex surface which is configured to be directlycontacted by an acetabulum socket in moveable engagement therewith.

There is also provided in accordance with a preferred embodiment of thepresent invention a prosthesis for use with a natural bone and includinga flexible bone interface element configured to be mounted onto thenatural bone, the flexible bone interface element including a unitaryelement molded of a single material and having a contact surface whichis configured to directly contact the natural bone in generally staticengagement therewith, and wherein the contact surface is configured witha configuration-pattern including of bone contact surface portionsdefined by channels surrounding the bone contact surface portions, andwherein the channels have a bottom surface and walls surfaces. Theflexible bone interface element being formed of material, which is moreflexible than bone material of the natural bone.

There is further provided in accordance with a preferred embodiment ofthe present invention A prosthesis for use with a natural bone andincluding a flexible bone interface element configured to be mountedonto the natural bone, the flexible bone interface element including aunitary element molded of a single material and having a contact surfacewhich is configured to directly contact the natural bone in generallystatic engagement therewith, and wherein the contact surface isconfigured with a configuration-pattern including of surface recessportions defined by bone contact ridges surrounding the surface recessportions, and wherein the surface recess portions have a bottom surfaceand walls surfaces. The flexible bone interface element being formed ofmaterial, which is more flexible than bone material of the natural bone.

Further in accordance with a preferred embodiment of the presentinvention the configuration-pattern of the contact surface is of afractal design including of bone contact surface portions defined bychannels surrounding bone contact surface portions.

Preferably, the contact surface is convex. Alternatively oradditionally, the contact surface is concave.

Still further in accordance with a preferred embodiment of the presentinvention the wall surfaces of channels are inclined inwardly creatingan undercut section with a wider lower dimension and an narrower upperdimension.

Additionally in accordance with a preferred embodiment of the presentinvention the prosthesis (convex) includes a configuration-pattern ofthe bone contact surface portions is of an hexagonal geometry.

Further in accordance with a preferred embodiment of the presentinvention the configuration-pattern of the bone contact surface portionsis of a spiral geometry defined by spiral channels.

Preferably, spiral bone contact surface portions are of a multiple entryspiral type.

Additionally or alternatively, the configuration-pattern of the bonecontact surface portions is of a wavy geometry (tire like treads).

Further in accordance with a preferred embodiment of the presentinvention the configuration-pattern of the bone contact surface portionsis of meshed pattern defined by the absence of a polka dot pattern.

Still further in accordance with a preferred embodiment of the inventionthe configuration-pattern of the bone contact surface portions is of anhexagonal geometry.

Additionally the configuration-pattern of the bone contact surfaceportions is of a spiral geometry defined by spiral channels.

Further in accordance with a preferred embodiment of the presentinvention the prosthesis (concave) includes a configuration-pattern ofthe bone contact surface portions, which includes a meshed patterndefined by the absence of a polka dot pattern.

Still further in accordance with a preferred embodiment of the presentinvention the bone contact surface and peripheral channels surfaces isconfigured with a rough (not smooth) texture.

Additionally in accordance with a preferred embodiment of the presentinvention the bone contact surface and peripheral channels surfaces istreated by atomic surface treatment.

Further in accordance with a preferred embodiment of the presentinvention the bone contact surface and peripheral channels surfaces isat least partially coated with a bioactive substance stimulatingbone-growth enhancing implant fixation to bone.

Preferably, the bioactive substance is Hydroxyapatite (HA:Ca10(PO4)6(OH)2).

In accordance with another preferred embodiment of the present inventiona mesh of metal is configured in channels generally in a floatingposition mostly clear of bottom and walls of the channels.Alternatively, a mesh of composite material is configured in channelsgenerally in a floating positioning mostly clear of bottom and walls ofthe channels. Preferably, the composite material includes carbon.Additionally or alternatively, the composite material includes KEVLAR®.Additionally or alternatively, the composite material includes DYNEEMA®.

Preferably, the mesh is embedded within bone contact surfaces.Alternatively, the mesh is embedded within non-bone contact surfaces.

There is further provided in accordance with another preferredembodiment of the present invention an artificial meniscus implantassembly formed by molding of polyurethane. Preferably, the artificialmeniscus implant assembly includes a convex articulation surface and aconcave articulation surface. Additionally, the artificial meniscusimplant assembly also includes a bone snap-fit engagement element.Additionally or alternatively, the artificial meniscus implant assemblyalso includes at least one thoroughgoing aperture. Preferably, theartificial meniscus implant assembly also includes at least one tissuesecure assembly.

In accordance with another preferred embodiment of the present inventionthe tissue secure assembly includes an inner grip element and a clip,and the clip has insert elements formed on each end thereof.

There is also provided in accordance with yet another preferredembodiment of the present invention an artificial patella surfaceelement formed by molding of polyurethane.

Preferably, the artificial patella surface element includes a concavearticulation surface. Additionally or alternatively, the artificialpatella surface element includes an outer peripheral protrusion.Preferably, the outer peripheral protrusion is arranged for snap-fitengagement with a corresponding recess provided by machining of apatella. In accordance with another preferred embodiment of the presentinvention, the artificial patella surface element also includes at leastone thoroughgoing aperture.

Preferably, the artificial patella surface element is constructed toallow for deformation in response to an impact force. Additionally, thedeformation provides a shock-absorbing effect to provide protection fromthe impact force. Additionally or alternatively, the patella surfaceelement returns to its original orientation after the deformation.

There is still further provided in accordance with still anotherpreferred embodiment of the present invention an artificial humeralsurface element formed by molding of polyurethane.

Preferably, the artificial humeral surface element includes a concavesaddle shape surface for articulation with an ulna. Alternatively, theartificial humeral surface element includes a convex generally sphericalsurface for articulation with a radius.

Preferably, the artificial humeral surface element includes a peripheralprotrusion element. Additionally, the peripheral protrusion element isarranged for snap-fit engagement with corresponding grooves formed bymachining the humerus.

There is yet further provided in accordance with another preferredembodiment of the present invention, an artificial ulnar surface elementformed by molding of polyurethane.

Preferably, the artificial ulnar surface element includes a concavesaddle shape surface for articulation with a humerus. Additionally, theartificial ulnar surface element includes a peripheral protrusionelement. Preferably, the peripheral protrusion element is arranged forsnap-fit engagement with corresponding grooves formed by machining theulna.

There is also provided in accordance with yet another preferredembodiment of the present invention an artificial radial surface elementformed by molding of polyurethane.

Preferably, the artificial radial surface element includes a concavegenerally spherical surface for articulation with a humerus.Additionally, the artificial radial surface element includes aperipheral protrusion element. Preferably, the peripheral protrusionelement is arranged for snap-fit engagement with corresponding groovesformed by machining the radius.

In accordance with another preferred embodiment of the presentinvention, the implantable artificial socket for a joint is foldable.

Additionally, the implantable artificial socket for a joint alsoincludes a deformation control element. Additionally, the deformationelement also includes a fluid absorption layer.

Further in accordance with another preferred embodiment of the presentinvention the implantable artificial socket for a joint also includes aradio opaque ring element.

In accordance with yet another preferred embodiment of the presentinvention the implantable artificial socket for a joint also includes abioactive coating. Preferably, the bioactive coating is formed by gritblasting. Alternatively, the bioactive coating is formed by spraying. Inaccordance with another preferred embodiment, the bioactive coating alsoincludes an elastomer.

In accordance with still another preferred embodiment, the implantableartificial socket for a joint also includes an elastomer coating on anarticulating surface.

In accordance with yet another preferred embodiment of the presentinvention, the implantable artificial socket for a joint also includes athickened portion corresponding to the natural acetabular notch.

Still further in accordance with another preferred embodiment of thepresent invention, the implantable artificial socket for a joint alsoincludes an extended portion to prevent dislocation of the naturalfemoral head following insertion thereof Alternatively, the implantableartificial socket for a joint also includes an extended portion toprevent dislocation of an artificial femoral head following insertionthereof.

In accordance with still another preferred embodiment of the presentinvention, the implantable artificial socket for a joint also includesrecessed surface portions. Preferably, the recessed surface portions areinterconnected. Additionally or alternatively, the recessed surfaceportions provide for the accumulation of synovial fluid. Preferably, thesynovial fluid is provided to lubricate an articulation surface of theartificial socket.

In accordance with another preferred embodiment of the presentinvention, the implantable artificial femoral head resurfacing elementis foldable.

Additionally, the implantable artificial femoral head resurfacingelement also includes a deformation control element. Additionally, thedeformation element also includes a fluid absorption layer.

Further in accordance with another preferred embodiment of the presentinvention the implantable artificial femoral head resurfacing elementalso includes a radio opaque ring element.

In accordance with yet another preferred embodiment of the presentinvention the implantable artificial femoral head resurfacing elementalso includes a bioactive coating. Preferably, the bioactive coating isformed by grit blasting. Alternatively, the bioactive coating is formedby spraying. In accordance with another preferred embodiment, thebioactive coating also includes an elastomer.

In accordance with still another preferred embodiment, the implantableartificial femoral head resurfacing element also includes an elastomercoating on an articulating surface.

Further in accordance with another preferred embodiment of the presentinvention the implantable artificial femoral head resurfacing elementalso includes a femoral head inner face element. Preferably, the femoralhead interface element is arranged for snap-fit engagement withcorresponding grooves formed by machining the femur. Alternatively, thefemoral head interface element is arranged for press fit engagement witha corresponding seating location formed by machining the femur.Additionally, the implantable artificial femoral head resurfacingelement is arranged for snap-fit engagement with the femoral headinterface element. Alternatively, the femoral head resurfacing elementis arranged for press fit engagement with the femoral head interfaceelement.

In accordance with still another preferred embodiment of the presentinvention, the implantable artificial femoral head resurfacing elementalso includes recessed surface portions. Preferably, the recessedsurface portions are interconnected. Additionally or alternatively, therecessed surface portions provide for the accumulation of synovialfluid. Preferably, the synovial fluid is provided to lubricate anarticulation surface of the artificial socket.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description, taken in conjunction with thedrawings in which:

FIGS. 1A, 1B and 1C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial socket for theacetabulum constructed and operative in accordance with a preferredembodiment of the present invention;

FIGS. 2A, 2B and 2C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial socket for theacetabulum constructed and operative in accordance with anotherpreferred embodiment of the present invention;

FIGS. 3A, 3B and 3C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial socket for theacetabulum constructed and operative in accordance with still anotherpreferred embodiment of the present invention;

FIGS. 4A, 4B and 4C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial socket for theacetabulum constructed and operative in accordance with yet anotherpreferred embodiment of the present invention;

FIGS. 5A, 5B and 5C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial socket for theacetabulum constructed and operative in accordance with a furtherpreferred embodiment of the present invention;

FIGS. 6A, 6B and 6C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial femoral headresurfacing element constructed and operative in accordance with apreferred embodiment of the present invention;

FIGS. 7A, 7B and 7C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial femoral headresurfacing element constructed and operative in accordance with anotherpreferred embodiment of the present invention;

FIGS. 8A, 8B and 8C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial femoral headresurfacing element constructed and operative in accordance with stillanother preferred embodiment of the present invention;

FIGS. 9A, 9B and 9C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial femoral headresurfacing element constructed and operative in accordance with yetanother preferred embodiment of the present invention;

FIGS. 10A, 10B, and 10C are respective pictorial, sectional andpartially cut away illustrations of an implantable artificial femoralhead resurfacing element constructed and operative in accordance with afurther preferred embodiment of the present invention;

FIGS. 11A and 11B are respective exploded view and assembled viewillustrations of the implantable artificial socket of FIGS. 1A-1C in atotal hip replacement environment;

FIGS. 12A and 12B are respective exploded view and assembled viewillustrations of the implantable artificial socket of FIGS. 1A-1C in apartial hip replacement environment;

FIGS. 13A and 13B are respective exploded view and assembled viewillustrations of the implantable artificial socket of FIGS. 1A-1C andthe implantable artificial femoral head resurfacing element of FIGS.6A-6C in a total hip resurfacing environment;

FIGS. 14A and 14B are respective exploded view and assembled viewillustrations of the implantable artificial femoral head resurfacingelement of FIGS. 6A-6C in a hemi hip resurfacing environment;

FIGS. 15A, 15B and 15C are respectively, an illustration of anarticulation surface, a sectional illustration and an illustration of abone engagement surface, of an implantable artificial socket for theglenoid constructed and operative in accordance with a preferredembodiment of the present invention;

FIGS. 16A, 16B and 16C are respectively, an illustration of anarticulation surface, a sectional illustration and an illustration of abone engagement surface, of an implantable artificial socket for theglenoid constructed and operative in accordance with another preferredembodiment of the present invention;

FIGS. 17A, 17B and 17C are respectively, an illustration of anarticulation surface, a sectional illustration and an illustration of abone engagement surface, of an implantable artificial socket for theglenoid constructed and operative in accordance with still anotherpreferred embodiment of the present invention;

FIGS. 18A, 18B and 18C are respectively, an illustration of anarticulation surface, a sectional illustration and an illustration of abone engagement surface, of an implantable artificial socket for theglenoid constructed and operative in accordance with yet anotherpreferred embodiment of the present invention;

FIGS. 19A, 19B and 19C are respectively, an illustration of anarticulation surface, a sectional illustration and an illustration of abone engagement surface, of an implantable artificial socket for theglenoid constructed and operative in accordance with a further preferredembodiment of the present invention;

FIGS. 20A, 20B and 20C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial humeral head surfaceelement constructed and operative in accordance with a preferredembodiment of the present invention;

FIGS. 21A, 21B and 21C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial humeral head surfaceelement constructed and operative in accordance with another preferredembodiment of the present invention;

FIGS. 22A, 22B and 22C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial humeral head surfaceelement constructed and operative in accordance with still anotherpreferred embodiment of the present inventions;

FIGS. 23A, 23B and 23C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial humeral head surfaceelement constructed and operative in accordance with yet anotherpreferred embodiment of the present invention;

FIGS. 24A, 24B and 24C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial humeral head surfaceelement constructed and operative in accordance with a further preferredembodiment of the present invention;

FIGS. 25A and 25B are respective exploded view and assembled viewillustrations of the implantable artificial glenoid socket of FIGS.15A-15C in a total shoulder replacement environment;

FIGS. 26A and 26B are respective exploded view and assembled viewillustrations of the implantable artificial glenoid socket of FIGS.15A-15C in a partial shoulder replacement environment;

FIGS. 27A and 27B are respective exploded view and assembled viewillustrations of the implantable artificial humeral head surface elementof FIGS. 20A-20C in a hemi shoulder resurface environment;

FIGS. 28A and 28B are respective exploded view and assembled viewillustrations of the implantable artificial glenoid socket of FIGS.15A-15C and the implantable artificial humeral head surface element ofFIGS. 20A-20C in a total shoulder resurfacing environment;

FIGS. 29A and 29B are pictorial illustrations showing an implantableartificial medial meniscus implant assembly constructed and operative inaccordance with a preferred embodiment of the present invention;

FIGS. 30A and 30B are first and second pictorial illustrations of animplantable artificial patella surface element constructed and operativein a pre installation stage in accordance with a preferred embodiment ofthe present invention;

FIGS. 31A, 31B and 31C are, respectively, a pictorial illustration andsectional illustrations of the implantable artificial patella surfaceelement of FIGS. 30A and 30B installed in patella;

FIGS. 32A and 32B are sectional illustrations of an implantableartificial patella surface element of FIGS. 30A and 30B in a patellareplacement environment;

FIGS. 33A, 33B, 33C, 33D, 33E and 33F are respective first and secondpictorial, and first, second, third and fourth partially cut awaysectional illustrations of a pair of implantable artificial humeralelbow surface elements constructed and operative in accordance with apreferred embodiment of the present invention;

FIGS. 34A, 34B, 34C, 34D, 34E and 34F are respective first and secondpictorial, and first, second, third and fourth sectional illustrationsof a pair of implantable artificial ulna and radius elbow elementsconstructed and operative in accordance with a preferred embodiment ofthe present invention;

FIGS. 35A and 35B are respective exploded view and assembled viewillustrations of the implantable artificial humeral elbow elements ofFIGS. 33A-33F in a partial elbow replacement environment;

FIGS. 36A and 36B are respective exploded view and assembled viewillustrations of the implantable artificial ulna and radius elbowelements of FIGS. 34A-34F in a partial elbow replacement environment;

FIG. 37 is an assembled view illustration of the implantable humeralelbow elements of FIGS. 33A-33F and the implantable artificial ulna andradius elements of FIGS. 34A-34F in a total elbow replacementenvironment;

FIGS. 38A, 38B, 38C and 38D are, respectively, a partially cut awayillustration and an exploded view illustration of a groove reaming tool,and exploded and assembled view illustrations of a portion of the groovereaming tool, constructed and operative in accordance with a preferredembodiment of the present invention;

FIGS. 39A and 39B are illustrations of another portion of the groovereaming tool of FIGS. 38A, 38B, 38C and 38D in first and secondoperative orientations;

FIGS. 40A, 40B, 40C, 40D, 40E, 40F and 40G are simplified pictorialillustrations of various stages in groove reaming of an acetabulum inaccordance with a preferred embodiment of the present invention;

FIGS. 41A, 41B, 41C and 41D are sectional illustrations showingalternative reamed acetabulum configurations;

FIGS. 42A and 42B are simplified pictorial illustrations of introductionand pre-snap fit placement of an implantable artificial femoral headresurfacing element adjacent a reamed femoral head in accordance withtwo alternative embodiments of the present invention;

FIGS. 43A and 43B are simplified pictorial illustrations of introductionand pre-snap fit placement of an implantable artificial acetabularsocket adjacent a reamed acetabulum in accordance with two alternativeembodiments of the present invention;

FIGS. 44A, 44B, 44C and 44D are, respectively, a simplified pictorialillustration and sectional illustrations of a snap-fit installation ofan implantable artificial acetabular socket in a reamed acetabulum inaccordance with a preferred embodiment of the present invention;

FIGS. 45A and 45B are a simplified pictorial illustration and asectional illustrated of a final stave in snap-fit installation of animplantable artificial acetabular socket in a reamed acetabulum inaccordance with a preferred embodiment of the present invention;

FIGS. 46A, 46B, 46C and 46D are respectively, a pictorial illustration,two different sectional views and a partially cut away pictorialillustration of an implantable artificial acetabular socket constructedand operative in accordance with a further preferred embodiment of thepresent invention;

FIGS. 47A, 47B and 47C are respectively, a pictorial and two partiallycut away illustrations of an implantable artificial acetabular socketconstructed and operative in accordance with another preferredembodiment of the present invention;

FIGS. 48A, 48B, 48C and 48D are partially cut away pictorialillustrations of an implantable artificial acetabular socket constructedand operative in accordance with still another preferred embodiment ofthe present invention;

FIGS. 49A and 49B are respective pictorial and partially cut awayillustrations of an implantable artificial acetabular socket constructedand operative in accordance with yet another preferred embodiment of thepresent invention;

FIGS. 50A and 50B are respective pictorial and partially cut awayillustrations of an implantable artificial acetabular socket constructedand operative in accordance with a further preferred embodiment of thepresent invention;

FIGS. 51A, 51B and 51C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial femoral headresurfacing element constructed and operative in accordance with afurther preferred embodiment of the present invention;

FIGS. 52A, 52B and 52C are respective pictorial, sectional and partiallyCut away illustrations of an implantable artificial femoral headresurfacing element constructed and operative in accordance with anotherpreferred embodiment of the present invention;

FIGS. 53A, 53B and 53C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial femoral headresurfacing element constructed and operative in accordance with stillanother preferred embodiment of the present invention;

FIGS. 54A, 54B and 54C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial femoral headresurfacing element constructed and operative in accordance with yetanother preferred embodiment of the present invention;

FIGS. 55A, 55B and 55C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial femoral headresurfacing element constructed and operative in accordance with afurther preferred embodiment of the present invention;

FIGS. 56A, 56B and 56C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial acetabular socketconstructed and operative in accordance with a further preferredembodiment of the present invention;

FIGS. 57A, 57B and 57C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial acetabular socketconstructed and operative in accordance with another preferredembodiment of the present invention;

FIGS. 58A and 58B are respective partially cut away pictorial andsectional illustrations of an implantable artificial acetabular socketconstructed and operative in accordance with still another preferredembodiment of the present invention;

FIGS. 59A and 59B are respective partially cut away pictorial andsectional illustrations of an implantable artificial acetabular socketconstructed and operative in accordance with yet another preferredembodiment of the present invention;

FIGS. 60A, 60B and 60C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial acetabular socketconstructed and operative in accordance with a further preferredembodiment of the present invention;

FIGS. 61A, 61B and 61C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial femoral headresurfacing element constructed and operative in accordance with afurther preferred embodiment of the present invention;

FIGS. 62A, 62B and 62C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial femoral headresurfacing element constructed and operative in accordance with anotherpreferred embodiment of the present invention;

FIGS. 63A and 63B are respective pictorial, sectional and partially cutaway illustrations of an implantable artificial femoral or humeral headresurfacing element constructed and operative in accordance with stillanother preferred embodiment of the present invention;

FIGS. 64A and 64B are respective pictorial and sectional illustrationsof an implantable artificial femoral or humeral head resurfacing elementconstructed and operative in accordance with yet another preferredembodiment of the present invention;

FIGS. 65A, 65B and 65C are respective pictorial, sectional and partiallycut away illustrations of an implantable artificial femoral or humeralhead resurfacing element constructed and operative in accordance with afurther preferred embodiment of the present invention;

FIGS. 66A, 66B, and 66C are respective pictorial, sectional andpartially cut away illustrations of an implantable artificial acetabularsocket constructed and operative in accordance with a further preferredembodiment of the present invention;

FIGS. 67A, 67B, and 67C are respective pictorial, sectional andpartially cut away illustrations of an implantable artificial acetabularsocket constructed and operative in accordance with another preferredembodiment of the present invention;

FIGS. 68A, 68B, and 68C are respective pictorial, sectional andpartially cut away illustrations of an implantable artificial acetabularsocket constructed and operative in accordance with yet anotherpreferred embodiment of the present invention;

FIGS. 69A, 69B, 69C and 69D are sectional illustrations of a hip jointemploying the implantable artificial acetabular sockets of FIGS. 66A-68Cimplanted in a reamed acetabulum;

FIGS. 70A, 70B, and 70C are respective pictorial, sectional andpartially cut away illustrations of an implantable artificial acetabularsocket constructed and operative in accordance with a further preferredembodiment of the present invention;

FIGS. 71A, 71B, and 71C are respective pictorial, sectional andpartially cut away illustrations of an implantable artificial acetabularsocket constructed and operative in accordance with another preferredembodiment of the present invention;

FIGS. 72A, 72B, and 72C are respective pictorial, sectional andpartially cut away illustrations of an implantable artificial acetabularsocket constructed and operative in accordance with still anotherpreferred embodiment of the present

FIGS. 73A and 73B are respective pictorial and sectional illustrationsof an implantable artificial femoral or humeral head resurfacing elementconstructed and operative in accordance with a further preferredembodiment of the present invention;

FIGS. 74A and 74B are respective pictorial and sectional illustrationsof an implantable artificial femoral or humeral head resurfacing elementconstructed and operative in accordance with another preferredembodiment of the present invention;

FIGS. 75A and 75B are respective pictorial and sectional illustrationsof an implantable artificial femoral or humeral head resurfacing elementconstructed and operative in accordance with still another preferredembodiment of the present invention;

FIGS. 76A and 76B are respective pictorial and sectional illustrationsof an implantable artificial acetabular socket constructed and operativein accordance with a further preferred embodiment of the presentinvention;

FIGS. 77A and 77B are respective pictorial and sectional illustrationsof an implantable artificial acetabular socket constructed and operativein accordance with another preferred embodiment of the presentinvention;

FIGS. 78A and 78B are respective pictorial and sectional illustrationsof an implantable artificial acetabular socket constructed and operativein accordance with still another preferred embodiment of the presentinvention;

FIGS. 79A and 79B are respective pictorial and sectional illustrationsof an implantable artificial acetabular socket constructed and operativein accordance with a further preferred embodiment of the presentinvention;

FIGS. 80A, 80B, and 80C are respective pictorial, sectional andpartially cut away illustrations of an implantable artificial acetabularsocket constructed and operative in accordance with another preferredembodiment of the present invention;

FIGS. 81A, 81B, and 81C are respective pictorial, sectional andpartially cut away illustrations of an implantable artificial acetabularsocket constructed and operative in accordance with still anotherpreferred embodiment of the present invention;

FIGS. 82A, 82B, and 82C are respective pictorial, sectional andpartially cut away illustrations of an implantable artificial acetabularsocket constructed and operative in accordance with a further preferredembodiment of the present invention;

FIG. 83 is a pictorial illustration of an implantable artificialacetabular socket constructed and operative in accordance with anotherpreferred embodiment of the present invention;

FIG. 84 is a pictorial illustration of an implantable artificialacetabular socket constructed and operative in accordance with stillanother preferred embodiment of the present invention;

FIGS. 85A and 85B are sectional illustrations of the installation of anartificial femoral head on a reamed femoral head, in accordance with apreferred embodiment of the present invention;

FIGS. 86A and 86B are sectional illustrations of the installation of anartificial femoral head on a reamed femoral head, in accordance withanother preferred embodiment of the present invention;

FIGS. 87A, 87B, 87C and 87D are sectional illustrations of variousstages of installation of a multi-part artificial femoral head on areamed femoral head in accordance with still another preferredembodiment of the present invention;

FIGS. 88A, 88B, 88C and 88D are sectional illustrations of variousstages of installation of a multi-part artificial femoral head on areamed femoral head in accordance with yet another preferred embodimentof the present invention;

FIGS. 89A and 89B are sectional illustrations of various stages ofinstallation of a multi-part artificial femoral head on a reamed femoralhead, in accordance with a further preferred embodiment of the presentinvention;

FIG. 90A is a sectional illustration of the installation of a multi-partartificial femoral head on a conventional stein in accordance with stillanother preferred embodiment of the present invention;

FIG. 90B is a sectional illustration of the installation of a multi-partartificial humeral head on a conventional stem in accordance with yetanother preferred embodiment of the present invention;

FIGS. 91A, 91B and 91C are sectional illustrations showing bone growthadjacent to an implanted acetabular socket in accordance with anotherpreferred embodiment of the present invention;

FIG. 92 is a simplified sectional illustration of a bone engagementsurface textured in accordance with another preferred embodiment of thepresent invention;

FIGS. 93A and 93B are simplified pictorial illustrations of a method ofmodifying the texture of a bone engagement surface of an artificialimplantation device, in accordance with another preferred embodiment ofthe present invention;

FIG. 94 is a simplified pictorial illustration of another method ofmodifying the textile of the bone engagement surface of an artificialimplantation device, in accordance with yet another preferred embodimentof the present invention; and

FIG. 95 is a simplified pictorial illustration of a spraying apparatuswhich may be used in the embodiment of FIG. 94.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to FIGS. 1A, 1B and 1C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial socket constructed and operative in accordancewith a preferred embodiment of the present invention and which isparticularly suitable for use in a hip joint.

As seen in FIGS. 1A, 1B and 1C, an implantable artificial acetabularsocket, designated by reference numeral 1100, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 1100 is ofgenerally uniform thickness, is symmetric about an axis 1101 and definesan hemispherical concave inner articulation surface 1102, having abeveled edge 1103, and a generally hemispherical outer bone engagementsurface 1104, which preferably has formed thereon, at any suitablelocation between its apex and its rim, a generally annular outwardlyextending protrusion 1106, preferably defining a generally annularundercut 1108. Alternatively, the protrusion 1106 may be any othersuitable non-annular, open or closed, generally peripheral, protrusion.The protrusion 1106 is preferably arranged for snap-fit engagement witha corresponding (groove formed by reaming of a bone, examples of whichare described hereinbelow.

Preferably, the protrusion 1106 has a cross-sectional configuration, ascan be readily seen in FIG. 1B, which is characterized in that anunderlying surface portion 1110 of protrusion 1106, at the undercut1108, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 1112 of protrusion 1106.

Reference is now made to FIGS. 2A, 2B and 2C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with another preferred embodiment of the present invention.

As seen in FIGS. 2A, 2B and 2C, an implantable artificial acetabularsocket, designated by reference numeral 1200, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 1200 is ofgenerally uniform thickness, is symmetric about an axis 1201 and definesan hemispherical inner articulation surface 1202, having a beveled edge1203, and a generally hemispherical outer bone engagement surface 1204which preferably has formed thereon, at any suitable location betweenits apex and its rim, a generally annular outwardly extending array 1206of discrete protrusions 1207, preferably defining a generally annulararray 1208 of undercuts 1209. Alternatively, the array 1206 may be anyother suitable non-annular, open or closed, generally peripheral, arrayof protrusions. The array 1206 of protrusions 1207 is preferablyarranged for snap-fit engagement with corresponding grooves formed interalia by reaming of a bone, examples of which are described hereinbelow.

Preferably, the protrusions 1207 have a cross-sectional configuration,as can be readily seen in FIG. 2B, which is characterized in that anunderlying surface portion 1210 of each protrusion 1207, at the undercut1209, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 1212 of the protrusion 1207.

Reference is now made to FIGS. 3A, 3B and 3C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with still another preferred embodiment of the presentinvention.

As seen in FIGS. 3A, 3B and 3C, an implantable artificial acetabularsocket, designated by reference numeral 1300, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 1300 is ofgenerally uniform thickness, is symmetric about an axis 1301 and definesan hemispherical inner articulation surface 1302, having a beveled edge1303, and a generally hemispherical outer bone engagement surface 1304which preferably has formed thereon, at any suitable location betweenits apex and its rim, a generally annular outwardly extending array 1306of discrete protrusions 1307, preferably defining a generally annulararray 1308 of undercuts 1309. Alternatively, the array 1306 may be anyother suitable non-annular, open or closed, generally peripheral, arrayof protrusions. The array 1306 of protrusions 1307 is preferablyarranged for snap-fit engagement with corresponding recesses formedinter alia by suitable machining of a bone.

Preferably, the protrusions 1307 have a generally button-likeconfiguration which is symmetric about an axis 1310 and include a bodyportion 1311 and an enlarged head portion 1312, as can be readily seenin FIG. 3B. Protrusions 1307 are generally characterized in that anunderlying surface portion 1313 of each protrusion 1307 definesperipheral undercut 1309 with respect to axis 1310.

Reference is now made to FIGS. 4A, 4B and 4C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with yet another preferred embodiment of the presentinvention.

As seen in FIGS. 4A, 4B and 4C, an implantable artificial acetabularsocket, designated by reference numeral 1400, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 1400 is ofgenerally uniform thickness, is symmetric about an axis 1401 and definesan hemispherical inner articulation surface 1402, having a beveled edge1403, and a generally hemispherical outer bone engagement surface 1404which preferably has formed thereon, at any suitable location betweenits apex and its rim, a generally annular inwardly extending recess1406, preferably defining a generally annular undercut 1408.Alternatively, the recess 1406 may be any other suitable non-annular,open or closed, generally peripheral, recess. The recess 1406 ispreferably arranged for snap-fit engagement with a correspondingprotrusion formed by reaming, of a bone, examples of which are describedhereinbelow.

Preferably, the recess 1406 has a cross-sectional configuration, as canbe readily seen in FIG. 4B, which is characterized in that an overlyingsurface portion 1410 of recess 1406, at the undercut 1408, defines aslope which is sharper than a corresponding slope of an underlyingsurface portion 1412 of recess 1406.

Reference is now made to FIGS. 5A, 5B and 5C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with still another preferred embodiment of the presentinvention.

As seen in FIGS. 5A, 5B and 5C, an implantable artificial acetabularsocket, designated by reference numeral 1500, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 1500 is ofgenerally uniform thickness, is symmetric about an axis 1501 and definesan hemispherical inner articulation surface 1502, having a beveled edge1503, and a generally hemispherical outer bone engagement surface 1504which preferably has formed thereon, at any suitable location betweenits apex and its rim, a generally annular inwardly extending array 1506of discrete recesses 1507, preferably defining a generally annular array1508 of undercuts 1509. Alternatively, the array 1506 may be any othersuitable non-annular, open or closed, generally peripheral, array ofrecesses. The array 1506 of recesses 1507 is preferably arranged forsnap-fit engagement with corresponding protrusions formed inter alia bysuitable machining of a bone.

Preferably, the recesses 1507 have a generally button-like configurationwhich is symmetric about an axis 1510 and include a body portion 1511and an enlarged head portion 1512, as can be readily seen in FIG. 5B.Recesses 1507 are generally characterized in that an overlying surfaceportion 1513 of each recess 1507 defines a peripheral undercut withrespect to axis 1510.

Reference is now made to FIGS. 6A, 6B and 6C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial femoral head resurfacing, element constructed andoperative in accordance with a preferred embodiment of the presentinvention. The implantable artificial femoral head resurfacing elementis intended for mounting onto a natural femoral head in accordance witha preferred embodiment of the present invention.

As seen in FIGS. 6A, 6B and 6C, an implantable artificial femoral headresurfacing element, designated by reference numeral 1600, is formedpreferably by injection molding of polyurethane. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial femoral head resurfacing element 1600is of generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 1601 and defines an hemisphericalouter articulation surface 1602 and a generally hemispherical inner boneengagement surface 1604, having a beveled edge 1605, which preferablyhas formed thereon, at any suitable location between its apex and itsrim, a generally annular inwardly extending protrusion 1606, preferablydefining a generally annular undercut 1608. Alternatively, theprotrusion 1606 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The protrusion 1606 is preferablyarranged for snap-fit engagement with a corresponding groove formed byreaming of a femoral head.

Preferably, the protrusion 1606 has a cross-sectional configuration, ascan be readily seen in FIG. 6B, which is characterized in that anunderlying surface portion 1610 of protrusion 1606, at the undercut1608, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 1612 of protrusion 1606.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial femoral head resurfacingelement 1600 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 7A, 7B and 7C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial femoral head resurfacing element constructed andoperative in accordance with another preferred embodiment of the presentinvention.

As seen in FIGS. 7A, 7B and 7C, an implantable artificial femoral headresurfacing element, designated by reference numeral 1700, is formedpreferably by injection molding of polyurethane. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial femoral head resurfacing element 1700is of generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 1701 and defines an hemisphericalouter articulation surface 1702 and a generally hemispherical inner boneengagement surface 1704, having a beveled edge 1705, which preferablyhas formed thereon, at any suitable location between its apex and itsrim, a generally annular inwardly extending array 1706 of discreteprotrusions 1707, preferably defining a generally annular array 1708 ofundercuts 1709. Alternatively, the array 1706 may be any other suitablenon-annular, open or closed, generally peripheral, array of protrusions.The array 1706 of protrusions 1707 is preferably arranged for snap-fitengagement with corresponding grooves formed inter alia by reaming of afemoral head.

Preferably, the protrusions 1707 have a cross-sectional configuration,as can be readily seen in FIG. 7B, which is characterized in that anunderlying surface portion 1710 of each protrusion 1707, at the undercut1709, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 1712 of the protrusion 1707.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial femoral head resurfacingelement 1700 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 8A, 8B and 8C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial femoral head resurfacing element constructed andoperative in accordance with still another preferred embodiment of thepresent invention.

As seen in FIGS. 5A, 5B and 8C, an implantable artificial femoral headresurfacing element, designated by reference numeral 1800, is formedpreferably by injection molding of polyurethane. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial femoral head resurfacing element 1800is of generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 1801 and defines an hemisphericalouter articulation surface 1802 and a generally hemispherical inner boneengagement surface 1804, having a beveled edge 1805, which preferablyhas formed thereon, at any suitable location between its apex and itsrim, a generally annular inwardly extending array 1806 of discreteprotrusions 1807, preferably defining a generally annular array 1808 ofundercuts 1809. Alternatively, the array 1806 may be any other suitablenon-annular, open or closed, generally peripheral, array of protrusions.The array 1806 of protrusions 1807 is preferably arranged for snap-fitengagement with corresponding recesses formed inter alia by suitablemachining of a femoral head.

Preferably, the protrusions 1807 have a generally button-likeconfiguration which is symmetric about an axis 1810 and include a bodyportion 1811 and an enlarged head portion 1812, as can be readily seenin FIG. 8B. Protrusions 1807 are generally characterized in that anunderlying surface portion 1813 of each protrusion 1807 defines theperipheral undercut 1809 with respect to axis 1810.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial femoral head resurfacingelement 1800 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 9A, 9B and 9C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial femoral head resurfacing element constructed andoperative in accordance with yet another preferred embodiment of thepresent invention.

As seen in FIGS. 9A, 9B and 9C, an implantable artificial femoral headresurfacing element, designated by reference numeral 1900, is formedpreferably by injection molding of polyurethane. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial femoral head resurfacing element 1900is of generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 1901 and defines an hemisphericalouter articulation surface 1902 and a generally hemispherical inner boneengagement surface 1904, having a beveled edge 1905, which preferablyhas formed thereon, at any suitable location between its apex and itsrim, a generally annular outwardly extending recess 1906, preferablydefining a generally annular undercut 1908. Alternatively, the recess1906 may be any other suitable non-annular, open or closed, generallyperipheral, protrusion. The recess 1906 is preferably arranged forsnap-fit engagement with a corresponding protrusion formed by reaming ofa femoral head.

Preferably, the recess 1906 has a cross-sectional configuration, as canbe readily seen in FIG. 9B, which is characterized in that an overlyingsurface portion 1910 of recess 1906, at the undercut 1908, defines aslope which is sharper than a corresponding slope of an underlyingsurface portion 1912 of recess 1906.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial femoral head resurfacingelement 1900 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 10A, 10B and 10C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial femoral head resurfacing element constructed andoperative in accordance with still another preferred embodiment of thepresent invention.

As seen in FIGS. 10A, 10B and 10C, an implantable artificial femoralhead resurfacing element, designated by reference numeral 2000, isformed preferably by injection molding of polyurethane. Preferredpolyurethane materials are described hereinbelow.

Preferably, implantable artificial femoral head resurfacing element 2000is of generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 2001 and defines an hemisphericalouter articulation surface 2002 and a generally hemispherical inner boneengagement surface 2004, having a beveled edge 2005, which preferablyhas formed thereon, at any suitable location between its apex and itsrim, a generally annular outwardly extending array 2006 of discreterecesses 2007, preferably defining a generally annular array 2008 ofundercuts 2009. Alternatively, the array 2006 may be any other suitablenon-annular, open or closed, generally peripheral, array of recesses.The array 2006 of recesses 2007 is preferably arranged for snap-fitengagement with corresponding protrusions formed inter alia by suitablemachining of a femoral head.

Preferably, the recesses 2007 have a generally button-like configurationwhich is symmetric about an axis 2010 and include a body portion 2011and an enlarged head portion 2012, as can be readily seen in FIG. 10B.Recesses 2007 are generally characterized in that an overlying surfaceportion 2013 of each recess 2007 defines peripheral undercut 2009 withrespect to axis 2010.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial femoral head resurfacingelement 2000 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 11A and 11B, which are respectiveexploded view and assembled view illustrations of the implantableartificial acetabular socket of FIGS. 1A-1C in a total hip replacementenvironment. As seen in FIGS. 11A and 11B, implantable artificialacetabular socket 1100 (FIGS. 1A-1C) is snap-fitted into a suitablymachined natural acetabulum of a patient. A conventional artificialfemoral head 2100 is mounted onto a conventional femoral stem 2102 andis arranged for articulation with articulation surface 1102 of socket1100.

Reference is now made to FIGS. 12A and 12B, which are respectiveexploded view and assembled view illustrations of the implantableartificial acetabular socket of FIGS. 1A-1C in a partial hip replacementenvironment. As seen in FIGS. 12A and 12B, implantable artificialacetabular socket 1100 (FIGS. 1A-1C) is snap-fitted into a suitablymachined natural acetabulum of a patient. A natural femoral head 2200 isarranged for articulation with articulation surface 1102 of socket 1100.

It is a particular feature of the embodiment of FIGS. 12A and 12B thatthe size and configuration of articulation surface 1102 of artificialacetabular socket 1100 is made to be identical to that of the naturalacetabular socket of the patient, in order that the natural femoral head2200 may articulate therewith with desired dimensional clearances andwithout requiring machining of the femoral head. The ability of thearticulation surface 1102 of socket 1100 to be identical to that of thenatural femoral head 2200 is provided by the flexibility and resiliencyof artificial acetabular socket 1100, which enables small adjustments inthe size and configuration of the articulation surface 1102 to berealized by suitably exact machining of the natural acetabular socket.

Reference is now made to FIGS. 13A and 13B, which are respectiveexploded view and assembled view illustrations of the implantableartificial acetabular socket of FIGS. 1A-1C and the implantableartificial femoral head resurfacing element of FIGS. 6A-6C in a totalhip resurfacing environment. As seen in FIGS. 13A and 13B, implantableartificial acetabular socket 1100 (FIGS. 1A-1C) is snap-fitted into asuitably machined natural acetabulum of a patient. A suitably machinednatural femoral head 2300 having the implantable artificial femoral headresurfacing element 1600 of FIGS. 6A-6C snap-fit mounted thereon isarranged for articulation of articulation surface 1602 thereof witharticulation surface 1102 of socket 1100.

Reference is now made to FIGS. 14A and 14B, which are respectiveexploded view and assembled view illustrations of the implantableartificial femoral head resurfacing element of FIGS. 6A-6C in a hemi hipresurfacing environment. As seen in FIGS. 14A and 14B, a suitablymachined natural femoral head 2400 having the implantable artificialfemoral head resurfacing element 1600 of FIGS. 6A-6C snap-fit mountedthereon is arranged for articulation of articulation surface 1602thereof with a natural articulation surface of a natural acetabulum.

It is a particular feature of the embodiment of FIGS. 14A and 14B thatthe size and configuration of articulation surface 1602 of artificialfemoral head resurfacing element 1600 is made to be identical to that ofthe natural acetabular socket of the patient, in order that the naturalfemoral head 2400 onto which artificial femoral head resurfacing element1600 is mounted may articulate therewith with desired dimensionalclearances and without requiring machining of the natural acetabulum.The ability of the articulation surface 1602 of femoral head resurfacingelement 1600 to be identical to that of the natural acetabulum isprovided by the flexibility and resiliency of artificial femoral headresurfacing element 1600, which enables small adjustments in the sizeand configuration of the articulation surface 1602 to be realized bysuitably exact machining of the femoral head.

Reference is now made to FIGS. 15A, 15B and 15C, which are respectively,an illustration of an articulation surface, a sectional illustration andan illustration of a bone engagement surface, of an implantableartificial glenoid socket constructed and operative in accordance with apreferred embodiment of the present invention and which is particularlyuseful for a shoulder joint.

As seen in FIGS. 15A, 15B and 15C, an implantable artificial glenoidsocket designated by reference numeral 2500, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial glenoid socket 2500 is of generallyuniform thickness and defines an articulation surface 2502, whichdefines a portion of a concave spherical surface, and a bone engagementsurface 2504. Bone engagement surface 2504 preferably has formed thereonmultiple protrusions. In the illustrated embodiment, there are providedinner and outer protrusions, respectively designated by referencenumerals 2506 and 2508, defining respective undercuts 2510 and 2512.Alternatively, protrusions 1506 and 2508 may be any other suitable openor closed protrusions. Protrusions 2506 and 2508 are preferably arrangedfor snap-fit engagement with corresponding grooves formed by machiningof the glenoid.

Reference is now made to FIGS. 16A, 16B and 16C, which are respectively,an illustration of an articulation surface, a sectional illustration andan illustration of a bone engagement surface, of an implantableartificial glenoid socket constructed and operative in accordance withanother preferred embodiment of the present invention.

As seen in FIGS. 16A, 16B and 16C, an implantable artificial glenoidsocket, designated by reference numeral 2600, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial glenoid socket 2600 is of generallyuniform thickness and defines an articulation surface 2602, whichdefines a portion of a concave spherical surface, and a bone engagementsurface 2604. Bone engagement surface 2604 preferably has formed thereonmultiple protrusions. In the illustrated embodiment, there are providedinner and outer arrays of protrusions, the arrays being respectivelydesignated by reference numerals 2606 and 2608, defining respectiveundercuts 2610 and 2612. Alternatively, protrusions of arrays 2606 and2608 may be any other suitable open or closed protrusions. Protrusions2606 and 2608 are preferably arranged for snap-fit engagement withcorresponding grooves formed by machining of the glenoid.

Reference is now made to FIGS. 17A, 17B and 17C, which are respectively,an illustration of an articulation surface, a sectional illustration andan illustration of a bone engagement surface, of an implantableartificial glenoid socket constructed and operative in accordance withyet another preferred embodiment of the present invention.

As seen in FIGS. 17A, 17B and 17C, an implantable artificial glenoidsocket, designated by reference numeral 2700, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial glenoid socket 2700 is of generallyuniform thickness and defines an articulation surface 2702, whichdefines a portion of a concave spherical surface, and a bone engagementsurface 2704. Bone engagement surface 2704 preferably has formed thereonmultiple protrusions. In the illustrated embodiment, there are providedan inner array of protrusions 2706 and an outer peripheral protrusion2708, defining respective undercuts 2710 and 2712. Alternatively,protrusions of array 2706 and protrusion 2708 may be any other suitableopen or closed protrusions. Protrusions of array 2706 and protrusion2708 are preferably arranged for snap-fit engagement with corresponding,grooves formed by machining of the glenoid.

Preferably, at least some of the protrusions of array 2706, heredesignated as protrusions 2713 have a generally button-likeconfiguration which is symmetric about an axis 2714 and include a bodyportion 2715 and an enlarged head portion 2716, as can be readily seenin FIG. 17B. Protrusions 2713 are generally characterized in that anunderlying surface portion 2717 of each protrusion 2713 definesperipheral undercut 2710 with respect to axis 2714.

Reference is now made to FIGS. 18A, 18B and 18C, which are respectively,an illustration of an articulation surface, a sectional illustration andan illustration of a bone engagement surface, of an implantableartificial glenoid socket constructed and operative in accordance withstill another preferred embodiment of the present invention.

As seen in FIGS. 18A, 18B and 18C, an implantable artificial glenoidsocket, designated by reference numeral 2800, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial glenoid socket 2800 is of generallyuniform thickness and defines an articulation surface 2802, whichdefines a portion of a concave spherical surface, and a bone engagementsurface 2804. Bone engagement surface 2804 preferably has formed thereonan inner recess and an outer protrusion, respectively designated byreference numerals 2806 and 2808, defining respective undercuts 2810 and2812. Alternatively, recess 2806 and protrusion 2808 may be any othersuitable, open or closed, recesses or protrusions, respectively. Recess2806 and protrusion 2808 are preferably arranged for snap-fit engagementwith corresponding protrusions and grooves respectively formed bymachining of the glenoid.

Reference is now made to FIGS. 19A, 19B and 19C, which are respectively,an illustration of an articulation surface, a sectional illustration andan illustration of a bone engagement surface, of an implantableartificial glenoid socket constructed and operative in accordance withyet another preferred embodiment of the present invention.

As seen in FIGS. 19A, 19B and 19C, an implantable artificial glenoidsocket, designated by reference numeral 2900, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial glenoid socket 2900 is of generallyuniform thickness and defines an articulation surface 2902, whichdefines a portion of a concave spherical surface, and a bone engagementsurface 2904. Bone engagement surface 2904 preferably has formed thereonmultiple recesses and/or protrusions. In the illustrated embodiment,there are provided an inner array of recesses 2906 and an outerperipheral protrusion 2908, defining respective undercuts 2910 and 2912.Alternatively, recesses of array 2906 and protrusion 2908 may be anyother suitable, open or closed, recesses and protrusion, respectively.Recesses of array 2906 and protrusion 2908 are preferably arranged forsnap-fit engagement with corresponding protrusions and groovesrespectively, formed by machining of the glenoid.

Preferably, at least some of the recesses of array 2906, here designatedas recesses 2913, have a generally button-like configuration which issymmetric about an axis 2914 and include a body portion 2915 and anenlarged head portion 2916, as can be readily seen in FIG. 19B. Recesses2913 are generally characterized in that an underlying surface portion2917 of each protrusion 2913 defines peripheral undercut 2910 withrespect to axis 2914.

Reference is now made to FIGS. 20A, 20B and 20C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial humeral head surface element constructed andoperative in accordance with a preferred embodiment of the presentinvention. The implantable artificial humeral head surface element isintended for mounting onto a natural humeral head in accordance with apreferred embodiment of the present invention.

As seen in FIGS. 20A, 20B and 20C, an implantable artificial humeralhead surface element, designated by reference numeral 3000, is formedpreferably by injection molding of polyurethane. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial humeral head surface element 3000 isof generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 3001 and defines an articulationsurface 3002, which defines a portion of a convex spherical surface, anda bone engagement surface 3004, having a beveled edge 3005, whichpreferably has formed thereon, at any suitable location between its apexand its rim, a generally annular inwardly extending protrusion 3006,preferably defining a generally annular undercut 3008. Alternatively,the protrusion 3006 may be any other suitable non-annular, open orclosed, generally peripheral, protrusion. The protrusion 3006 ispreferably arranged for snap-fit engagement with a corresponding grooveformed by reaming of a humeral head.

Preferably, the protrusion 3006 has a cross-sectional configuration, ascan be readily seen in FIG. 20B, which is characterized in that anunderlying surface portion 3010 of protrusion 3006, at the undercut3008, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 3012 of protrusion 3006.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial humeral head surface element3000 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 21A, 21B and 21C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial humeral head surface element constructed andoperative in accordance with another preferred embodiment of the presentinvention.

As seen in FIGS. 21A, 21B and 21C, an implantable artificial humeralhead surface element, designated by reference numeral 3100, is formedpreferably by injection molding of polyurethane. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial humeral head surface element 3100 isof generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 3101 and defines an articulationsurface 3102, which defines a portion of a convex spherical surface, anda bone engagement surface 3104, having a beveled edge 3105, whichpreferably has formed thereon, at any suitable location between its apexand its rim, a generally annular inwardly extending array 3106 ofdiscrete protrusions 3107, preferably defining a generally annular array3108 of undercuts 3109. Alternatively, the array 3106 may be any othersuitable non-annular, open or closed, generally peripheral, array ofprotrusions. The array 3106 of protrusions 3107 is preferably arrangedfor snap-fit engagement with corresponding grooves formed inter alia byreaming of a humeral head.

Preferably, the protrusions 3107 have a cross-sectional configuration,as can be readily seen in FIG. 21B, which is characterized in that anunderlying surface portion 3110 of each protrusion 3107, at the undercut3109, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 3112 of the protrusion 3107.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial humeral head surface element3100 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 22A, 22B and 22C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial humeral head surface element constructed andoperative in accordance with still another preferred embodiment of thepresent invention.

As seen in FIGS. 22A, 22B and 22C, an implantable artificial humeralhead surface element, designated by reference numeral 3200, is formedpreferably by injection molding of polyurethane. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial humeral head surface element 3200 isof generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 3201 and defines an articulationsurface 3202, which defines a portion of a convex spherical surface, anda bone engagement surface 3204, having a beveled edge 3205, whichpreferably has formed thereon, at any suitable location between its apexand its rim, a generally annular inwardly extending array 3206 ofdiscrete protrusions 3207, preferably defining a generally annular array3208 of undercuts 3209. Alternatively, the array 3206 may be any othersuitable non-annular, open or closed, generally peripheral, array ofprotrusions. The array 3206 of protrusions 3207 is preferably arrangedfor snap-fit engagement with corresponding recesses formed inter alia bysuitable machining of a humeral head.

Preferably, the protrusions 3207 have a generally button-likeconfiguration which is symmetric about an axis 3210 and include a bodyportion 3211 and an enlarged head portion 3212, as can be readily seenin FIG. 22B. Protrusions 3207 are generally characterized in that anunderlying surface portion 3213 of each protrusion 3207 definesperipheral undercut 3209 with respect to axis 3210.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial humeral head surface element3200 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 23A, 23B and 23C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial humeral head surface element constructed andoperative in accordance with yet another preferred embodiment of thepresent invention.

As seen in FIGS. 23A, 23B and 23C, an implantable artificial humeralhead surface element, designated by reference numeral 3300, is formedpreferably by injection molding of polyurethane. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial humeral head surface element 3300 isof generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 3301 and defines an articulationsurface 3302, which defines a portion of a convex spherical surface, anda bone engagement surface 3304, having a beveled edge 3305, whichpreferably has formed thereon, at any suitable location between its apexand its rim, a generally annular outwardly extending recess 3306,preferably defining a generally annular undercut 3308. Alternatively,the recess 3306 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The recess 3306 is preferably arrangedfor snap-fit engagement with a corresponding protrusion formed byreaming of a humeral head.

Preferably, the recess 3306 has a cross-sectional configuration, as canbe readily seen in FIG. 23B, which is characterized in that an overlyingsurface portion 3310 of recess 3306, at the undercut 3308, defines aslope which is sharper than a corresponding slope of an underlyingsurface portion 3312 of recess 3306.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial humeral head surface element3300 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 24A, 24B and 24C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial humeral head surface element constructed andoperative in accordance with still another preferred embodiment of thepresent invention.

As seen in FIGS. 24A, 24B and 24C, an implantable artificial humeralhead surface element, designated by reference numeral 3400, is formedpreferably by injection molding of polyurethane. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial humeral head surface element 3400 isof generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 3401 and defines an articulationsurface 3402, which defines a portion of a convex spherical surface, anda bone engagement surface 3404, having a beveled edge 3405, whichpreferably has formed thereon, at any suitable location between its apexand its rim, a generally annular outwardly extending array 3406 ofdiscrete recesses 3407, preferably defining a generally annular array3408 of undercuts 3409. Alternatively, the array 3406 may be any othersuitable non-annular, open or closed, generally peripheral, array ofrecesses. The array 3406 of recesses 3407 is preferably arranged forsnap-fit engagement with corresponding protrusions formed inter alia bysuitable machining of a humeral head.

Preferably, the recesses 3407 have a generally button-like configurationwhich is symmetric about an axis 3410 and include a body portion 3411and an enlarged head portion 3412, as can be readily seen in FIG. 24B.Recesses 3407 are generally characterized in that an overlying surfaceportion 3413 of each recess 3407 defines peripheral undercut 3409 withrespect to axis 3410.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial humeral head surface element3400 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 25A and 25B, which are respectiveexploded view and assembled view illustrations of the implantableartificial glenoid socket of FIGS. 11A-15C in a total shoulderreplacement environment. As seen in FIGS. 25A and 25B, implantableartificial glenoid socket 2500 (FIGS. 15A-15C) is snap-fitted into asuitably machined natural glenoid of a patient. A conventionalartificial humeral head 3500 is mounted onto a conventional humeral stem3502 and is arranged for articulation with articulation surface 2502 ofsocket 2500.

Reference is now made to FIGS. 26A and 26B, which are respectiveexploded view and assembled view illustrations of the implantableartificial glenoid socket of FIGS. 15A-15C in a partial shoulderreplacement environment. As seen in FIGS. 26A and 26B, implantableartificial glenoid socket 2500 (FIGS. 15A-15C) is snap-fitted into asuitably machined natural glenoid of a patient. A natural humeral head3600 is arranged for articulation with articulation surface 2502 ofsocket 2500.

It is a particular feature of the embodiment of FIGS. 26A and 26B thatthe size and configuration of articulation surface 2502 of artificialglenoid socket 2500 is made to be identical to that of the naturalglenoid socket of the patient, in order that the natural humeral head3600 may articulate therewith with desired dimensional clearances andwithout requiring machining of the humeral head. The ability of thearticulation surface 2502 of socket 2500 to be identical to that of thenatural humeral head is provided by the flexibility and resiliency ofartificial glenoid socket 2500, which enables small adjustments in thesize and configuration of the articulation surface 2502 to be realizedby suitably exact machining of the natural glenoid socket.

Reference is now made to FIGS. 27A and 27B, which are respectiveexploded view and assembled view illustrations of the implantableartificial humeral head surface element of FIGS. 20A-20C in a hemishoulder resurfacing environment. As seen in FIGS. 27A and 27B, asuitably machined natural humeral head 3650 having the implantableartificial humeral head surface element 3000 of FIGS. 20A-20C snap-fitmounted thereon is arranged for articulation of articulation surface3002 thereof with a natural articulation surface 3652 of a naturalglenoid.

It is a particular feature of the embodiment of FIGS. 27A and 27B thatthe size and configuration of articulation surface 3002 of artificialhumeral head surface element 3000 is made to be identical to that of thenatural glenoid socket 3652 of the patient, in order that the naturalhumeral head 3650 onto which artificial humeral head surface element3000 is mounted may articulate therewith with desired dimensionalclearances and without requiring machining of the natural glenoid. Theability of the articulation surface 3002 of humeral head surface element3000 to be identical to that of the natural glenoid is provided by theflexibility and resiliency of artificial humeral head surface element3000, which enables small adjustments in the size and configuration ofthe articulation surface 3002 to be realized by suitably exact machiningof the humeral head.

Reference is now made to FIGS. 28A and 28B, which are respectiveexploded view and assembled view illustrations of the implantableartificial glenoid socket of FIGS. 15A-15C and the implantableartificial humeral head surface element of FIGS. 20A-20C in a totalshoulder resurfacing environment. As seen in FIGS. 28A and 28B,implantable artificial adenoid socket 2500 (FIGS. 15A-15C) issnap-fitted into a suitably machined natural glenoid of a patient. Asuitably machined natural humeral head 3700 having the implantableartificial humeral head surface element 3000 of FIGS. 20A-20C snap-fitmounted thereon is arranged for articulation of articulation surface3002 thereof with articulation surface 2502 of socket 2500.

Reference is now made to FIGS. 29A and 29B, which are pictorialillustrations showing an implantable artificial medial meniscus implantassembly constructed and operative in accordance with a preferredembodiment of the present invention. As seen in FIGS. 29A and 29B, animplantable artificial medial meniscus implant assembly, designated byreference numeral 4060, is formed preferably by injection molding ofpolyurethane. Preferred polyurethane materials are describedhereinbelow.

Preferably, implantable meniscus implant assembly 4060 defines a concavearticulation surface 4061, which is defined on an articulation portion4063, a convex articulation surface 4064, which is defined on anarticulation portion 4065, and a bone snap-fit engagement element 4066for locking engagement with a matching machined tibia recess (not shown)which is defined on a bone anchoring portion 4067. Articulation portion4063 preferably has formed thereon multiple protrusions 4068 forsnap-fit engagement with multiple recesses 4069 defined on articulationportion 4065.

Articulation portions 4063 and 4065 may alternatively be formed as onepiece constructed to fold and snap-fit on itself, only in some portionsof the snap-fit engagement regions provided in assembly 4060.

Articulation portion 4063 has formed, in articulation surface 4061, aplurality of thoroughgoing apertures 4070, which, as describedhereinbelow, allow synovial fluid to pass therethrough for lubricationof the articulation surface 4061 when articulation portion 4063articulates with the articulation surface of the femur. Articulationportion 4065 has formed in articulation surface 4064 a plurality ofthoroughgoing apertures 4071, which, as described hereinbelow, allowsynovial fluid to pass therethrough for lubrication of the articulationsurface 4064 when articulation portion 4065 articulates with thearticulation surface of the tibia.

The application of force on articulation surface 4061 or articulationsurface 4064 causes the corresponding articulation portion 4063 or 4065to be resiliently displaced inwardly, thus causing synovial fluid,located between the articulation portion 4063 and the articulationportion 4065 to be forced through apertures 4070 and 4071 so as to lieon and over articulation surfaces 4061 or 4064 and to provide enhancedlubrication for the articulation of articulation surfaces 4061 and 4064.

In accordance with a preferred embodiment of the present invention, inaddition to the snap-fit anchoring to the tibia by element 4066,implantable meniscus implant assembly 4060 is also securely positionedinto a sliding operational condition with respect to any of femurarticulating surface and tibia articulating surface by multiple tissuesecure assemblies 4074.

As seen in FIG. 29A, insert elements 4076 are securely assembled betweenarticulation portion 4063 and articulation portion 4065. As seen in FIG.29B, insert elements 4076 are formed on each end of clip 4077 shownripping from the outside a connecting tissue fraction 4078 of theconnecting tissue surrounding the knee joint.

Implantable meniscus implant assembly 4060 also comprises an inner gripelement 4079, shown in FIG. 29B gripping the connecting tissue fraction4078 from the inside. Tissue secure assembly 4074 defines a rounded edgeseat 4080 provided for slidingly securing the tissue fraction 4078 withrespect to the tissue secure assembly 4074. A first segment of seat 4080is formed as a recess on the inside surface of clip 4077 and a secondsegment of seat 4080 is formed as a recess on the outside surface ofgrip 4079.

Reference is now made to FIGS. 30A and 30B, which are pictorialillustrations of a pre installation stage of an implantable artificialpatella surface element, constructed and operative in accordance with apreferred embodiment of the present invention. FIG. 30A shows animplantable artificial patella surface element 4100, while FIG. 30Billustrates the preparation of the patella for implantation ofimplantable artificial patella surface element 4100. As seen in FIG.30A, implantable artificial patella surface element 4100 is formed,preferably, by injection molding of polyurethane. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial patella surface element 4100 definesa concave articulation surface 4102 and an outer peripheral protrusion4104 arranged for snap-fit engagement with a corresponding recess 4106provided by machining of patella 4110. Implantable artificial patellasurface element 4100 also preferably includes a plurality ofthoroughgoing apertures 4108 to allow synovial fluid to passtherethrough for lubrication of the articulation surface 4102, asdescribed hereinbelow with reference to FIG. 32B.

As seen in FIG. 30B, recess 4106 is formed with an inner circumferentialundercut 4112. A planar surface 4114, an undercut closed circumferentialgroove 4116 and an additional planar surface 4117 are provided bymachining of the patella 4110.

Reference is now made to FIGS. 31A, 31B and 31C, which show artificialpatella surface element 4100 of FIG. 30A installed in a patella 4110,prepared as shown in FIG. 30B, in accordance with a preferred embodimentof the present invention. As seen in FIG. 31B outer peripheralprotrusion 4104 of implantable artificial patella surface element 4100defines an undercut 4120 configured for a snap-fit engagement withundercut 4112 machined in recess 4106 in patella 4110. In addition,artificial patella surface element 4100 defines an inner snap-fitcircumferential locking portion 4115 comprising undercut 4122 configuredfor a snap-fit engagement with groove 4116 machined in patella 4110. Itis appreciated that artificial patella surface element 4100 isconfigured with an inner free surface 4124 positioned remote from planarsurface 4117 creating a void 4126. Articulating portion 4130 ofartificial patella surface element 4100 is external to inner freesurface 4124 and is defined by circumferential snap-fit locking portion4115. Articulating portion 4130 of artificial patella surface element4100 also preferably includes apertures 4108 to allow synovial fluid topass therethrough for lubrication of the articulation surface 4102, asdescribed hereinbelow with reference to FIG. 32B.

Reference is now made to FIGS. 32A and 32B, which are sectionalillustrations of the implantable artificial patella surface element 4100of FIG. 30A in a patella replacement environment in operativeorientations where the joint is un-impacted and wherein the joint isimpacted.

In FIG. 32A, which shows an un-impacted joint, patella 4110 andartificial patella surface element 4100 are installed in an articulatingarrangement with lateral condyle 4140, medial condyle 4141 and trochleargroove 4142. The approximate center of articulation of the femur isshown as an axis 4143, and the approximate center of articulation of thearticulating portion 4130 of artificial patella surface element 4100 isshown as an axis 4144. Most of the articulating contact of artificialpatella surface element 4100 is performed by articulation portion 4130,providing a space 4146 between patella 4110 and lateral condyle 4140 anda space 4148 between patella 4110 and medial condyle 4141.

Articulating portion 4130 may undergo deformation when frontal impactforce is exerted on patella 4110. An example of such impact force is theimpact force here designated by arrow 4150. This frontal impact forceresults in an inward deformation of articulation portion 4130, thusproviding a shock-absorbing effect protecting the joint from beingdamaged by the impact force.

FIG. 32B shows the joint being impacted by a lateral impact force,designated here by arrow 4152, exerted on artificial patella surfaceelement 4100. The lateral impact force deflects patella 4110 sideways inrelation to the femoral condyles as can be seen from the shiftedposition of axis 4144 in relation to axis 4143. The flexibleconstruction of articulating portion 4130 allows a considerabledeformation from its original form without dislodgment of artificialpatella surface element 4100 from its anchoring engagement with patella4110. The deformation of articulating portion 4130 results in recoilenergy which returns the patella 4110 to its original orientation afterthe impact force dissipates.

In accordance with a preferred embodiment of the present invention,articulating portion 4130 includes apertures 4108 (FIG. 31A) to allowsynovial fluid to pass therethrough for lubrication of the articulationsurface 4102.

At least part of articulation portion 4130 is forced to be resilientlydisplaced toward any of lateral condyle 4140, medial condyle 4141 andtrochlear groove 4142, laterally by any of frontal impact force, lateralimpact force, flexation action of the knee joint and extension action ofthe knee joint. Such resilient displacement causes synovial fluid,located in void 4126, to be forced through apertures 4108 (FIG. 31A) soas to lie on and over articulation surface 4102 and to provide enhancedlubrication for the articulation of articulation surface 4102 ofarticulation portion 4130 with the femoral condyles 4140 and 4141 andtrochlear groove 4142.

Reference is now made to FIGS. 33A, 33B, 33C, 33D, 33E and 33F, whichare simplified illustrations of first and second implantable artificialhumeral elbow surface elements, constructed and operative in accordancewith another preferred embodiment of the present invention, which areparticularly useful for an elbow joint.

As seen in FIGS. 33A, 33B, 33D and 33E, an artificial humeral elbowsurface element 4180 is constructed for articulation with the ulna andan artificial humeral surface element 4182 is constructed forarticulation with the radius. Implantable artificial humeral surfaceelements 4180 and 4182 are formed, preferably, by injection molding ofpolyurethane. Preferred polyurethane materials are described

Preferably, implantable artificial humeral surface elements 4180 and4182 are of generally uniform thickness, and define, respectively, anarticulation surface 4184, which defines a portion of a concave saddleshape surface, and an articulation surface 4186, which defines a portionof a convex generally spherical surface, and respective bone engagementsurfaces 4188 and 4190. Bone engagement surfaces 4188 and 4190preferably have formed thereon respective peripheral protrusion elements4192 and 4194.

As seen in FIGS. 33C and 33F, peripheral protrusion elements 4192 and4194 define respective undercuts 4196 and 4198. Alternatively,protrusions elements 4192 and 4194 may be any other suitable open orclosed protrusions. Protrusions 4192 and 4194 are preferably arrangedfor snap-fit engagement with corresponding grooves formed by machiningof the humerus.

Reference is now made to FIGS. 34A, 34B, 34C, 34D, 34E and 34F, whichare simplified illustrations of an implantable artificial ulna surfaceelement and an implantable radius surface element, constructed andoperative in accordance with another preferred embodiment of the presentinvention, which are particularly useful for an elbow joint. As seen inFIGS. 34A, 34B, 34C, 34D, 34E and 34F, artificial ulna surface element4210 and artificial radius surface elements 4212 are constructed forarticulation with the humerus. Implantable artificial ulna surfaceelement 4210 and artificial radius surface element 4212 are formedpreferably by injection molding of polyurethane. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial ulna surface element 4210 andartificial radius surface elements 4212 are of generally uniformthickness and respectively define an articulation surface 4214, whichdefines a portion of a concave saddle shape surface, and an articulationsurface 4216, which defines a portion of a concave generally sphericalsurface, and respective bone engagement surfaces 4218 and 4220. Boneengagement surfaces 4218 and 4220 preferably have formed thereonrespective peripheral protrusion elements 4226 and 4228. Peripheralprotrusion elements 4226 and 4228 define respective undercuts 4232 and4234. Alternatively, protrusions elements 4226 and 4228 may be any othersuitable, open or closed protrusions. Protrusions 4226 and 4228 arepreferably arranged for snap-fit engagement with corresponding groovesformed by machining of the ulna and radius, respectively.

Reference is now made to FIGS. 35A and 35B, which are respectiveexploded view and assembled view illustrations of the implantableartificial humeral elbow elements of FIGS. 33A-33F in a partial elbowreplacement environment. FIG. 35A shows a pre installation stage, whileFIG. 35B shows the elements installed.

As seen in FIG. 35A, protrusion 4192 of implantable artificial humeralelbow element 4180 is preferably arranged for snap-fit engagement withcorresponding groove 4242 formed by machining of the humerus. Groove4242 is preferably formed with an undercut 4244 matching undercut 4196of protrusion 4192.

Protrusion 4194 of implantable artificial humeral elbow element 4182 ispreferably arranged for snap-fit engagement with corresponding groove4246 formed by machining of the humerus. Groove 4246 is preferablyformed with an undercut 4248 matching undercut 4198 of protrusion 4194.

FIG. 35B shows implantable artificial humeral elbow element 4180 andimplantable artificial humeral elbow element 4182 mounted onto ahumerus.

Reference is now made to FIGS. 36A and 36B, which are respectiveexploded view and assembled view illustrations of the implantableartificial ulna surface element 4210 and artificial radius surfaceelements 4212 of FIGS. 34A-34F in a partial elbow replacementenvironment. FIG. 36A shows a pre installation stage, while FIG. 36Bshows the elements installed.

As seen in FIG. 36A, protrusion 4226 of implantable artificial ulnasurface element 4210 is preferably arranged for snap-fit engagement witha corresponding groove 4252 formed by machining of the ulna. Groove 4252is preferably formed with an undercut 4254 matching undercut 4232 ofprotrusion 4226.

Protrusion 4228 of artificial radius surface element 4212 is preferablyarranged for snap-fit engagement with a corresponding groove 4256 formedby machining of the radius. Groove 4256 is preferably formed with anundercut 4258 matching undercut 4234 of protrusion 4228.

FIG. 36B shows implantable artificial ulna elbow element 4210 mountedonto an ulna and implantable artificial radius elbow element 4212mounted onto a radius.

Reference is now made to FIG. 37, which is a simplified illustration ofthe implantable humeral elbow elements of FIGS. 33A-33F and theimplantable artificial ulna and radius elements of FIGS. 34A-34F in atotal elbow replacement environment.

As seen in FIG. 37, implantable artificial humeral elbow element 4180and implantable artificial humeral elbow element 4182 are shown mountedonto a humerus. Implantable artificial ulna elbow element 4210 is shownmounted onto an ulna and implantable artificial radius elbow element4212 is shown mounted onto a radius.

Articulation surface 4184 of artificial humeral elbow element 4180articulates with articulation surface 4214 of artificial ulna elbowelement 4210. Articulation surface 4186 of artificial humeral elbowelement 4182 articulates with Articulation surface 4216 of artificialradius elbow element 4212.

Reference is now made to FIGS. 38A, 38B, 38C and 38D, which illustrate agroove reaming tool constructed and operative in accordance with apreferred embodiment of the present invention. As seen in FIGS. 38A and38B, a hand operated reaming tool 4800 is provided with a handle 4802,fixedly coupled to a shaft 4804. An elongate grip 4806 is rotatably andslidably mounted over shaft 4804 and axially engages an outwardlyextendible recess engagement element 4808, which is also rotatably andslidably mounted with respect to shaft 4804.

Outwardly extendible recess engagement element 4808 is preferably anintegrally formed element made of metal, such as spring steel, andincludes a generally hollow cylindrical portion 4810 formed with aplurality of axially extending slots 4812, which extend from a locationspaced from a top edge 4814 of the cylindrical portion 4810 towards andthrough a generally radially outwardly extending disk-like portion 4816.

It is appreciated that disk-like portion 4816 thus includes a pluralityof azimuthally separated segments 4818, each of which defines acontinuation of a corresponding azimuthally separated segment 4820 ofcylindrical portion 4810. Preferably, an outer edge 4822 of disk-likeportion 4816 is formed with a high friction engagement surface, such asa toothed surface.

It is seen that preferably disk-like portion 4816 is formed with acentral generally conical recess 4824 oil an underside surface 4826thereof.

A generally solid, centrally apertured conical element 4830 is rotatablymounted onto shaft 4804 such that a conical surface 4832 thereof isadapted to operatively engage conical recess 4824 in a manner that suchengagement produces radially outward displacement of segments 4818 ofdisk-like portion 4816.

Preferably, there is provided a retainer element 4840 which is rotatablymounted with respect to shaft 4804 and overlies disk-like portion 4816.Preferably retainer element 4840 includes depending plates 4842 whichengage interstices between segments 4818.

In accordance with a preferred embodiment of the invention, a groovecutter mounting element 4850 is fixedly mounted to shaft 4804 forrotation together therewith in response to rotation of handle 4802.Groove cutter mounting element 4850 preferably underlies conical element4830 and is separated therefrom by a washer 4852, to enable groovecutter mounting element 4850 to easily rotate with respect to conicalelement 4830.

An end element 4860 is rotatably mounted onto an end of shaft 4804,underlying groove cutter mounting element 4850 such that groove cuttermounting element 4850 is rotatable with respect thereto. End element4860 is preferably formed with a high friction engagement surface 4862,such as a toothed surface, on the underside thereof.

Groove cutter mounting element 4850 is preferably a generally hollowhemispherical element having a central hub 4864 which defines arectangular thoroughgoing aperture 4866 for receiving an end 4868 ofshaft 4804. Three extending recesses 4869, 4870 and 4871, respectively,are formed in an outer facing wall 4872 of hub 4864. A correspondinggenerally elongate aperture 4874 is formed in a wall 4875 of groovecutter mounting element 4850 opposite recesses 4869, 4870 and 4871.Aperture 4874 extends azimuthally beyond recesses 4869, 4870 and 4871.

A plurality of cutter elements 4880, preferably three in number, aretogether removably retained in groove cutter mounting element 4850. Asseen clearly in FIGS. 38C and 38D, the cutter elements 4880 arepreferably of similar configuration, but have at least one differingdimension. Each cutter element 4880 preferably is formed of a flat pieceof metal and includes a hook portion 4882, defining an undercut 4884, acentral portion 4886 and a cutting portion 4888, which defines a curvedcutting edge 4890 inwardly of which is defined an aperture 4892 having abeveled peripheral edge 4894.

Preferably, as seen clearly in FIG. 38D, the cutter elements 4880 arearranged such that their hook portions 4882 engage recesses 4869, 4870and 4871 and their cutting portions 4888 extend outwardly of wall 4875through aperture 4874. Preferably the extent of central portions 4886 ofcutter elements 4880 varies such that the amount that cutting portions4888 extend outwardly of wall 4875 varies as illustrated in FIG. 38D.Preferably, the cutting elements 4880 are arranged to provide a steppedincrease in the extent that the cutting portions 4888 extend outwardly,in the direction of operational rotation of the tool 4800.

Reference is now made to FIGS. 39A and 39B, which are illustrations ofanother portion of the groove reaming tool of FIGS. 38A and 38B in firstand second operative orientations. In a first, non-engagementorientation shown in FIG. 39A, when grip 3806 is not pushed downwardalong shaft 4804 towards groove cutter mounting element 4850 (FIGS. 38Aand 38B), outwardly extendible recess engagement element 4808 is notsubject to downward axial force and thus no axial force is appliedbetween recess 4824, on the underside surface 4826 thereof, and conicalelement 4830.

In a second, bone recess engagement orientation shown in FIG. 39B, grip4806 is pushed downward along shaft 4804 towards groove cutter mountingelement 4850 (FIGS. 38A and 38B), as indicated by an arrow 4896 andengages outwardly extendible recess engagement element 4808, forcingrecess 4824 on the underside surface 4826 thereof axially againstconical element 4830, as indicated by arrow 4897. This axial forcecauses radially outward displacement of segments 4818 of disk-likeportion 4816, as indicated by arrow 4898.

Reference is now made to FIGS. 40A-40G, which illustrate various stagesin groove reaming of an acetabulum in accordance with a preferredembodiment of the present invention preferably employing the apparatusof FIGS. 38A-38D.

FIG. 40A illustrates groove reaming tool 4800 prior to engagement withan acetabulum which has been previously reamed. It is seen that thecutting portions 4888 of cutter elements 4880 are aligned with anacetabulum notch 5000 and that the shaft 4804 is arranged along an axis5002 which is approximately coaxial with the axis of symmetry of thereamed acetabulum 5004, which axis of symmetry is designated byreference numeral 5006.

FIG. 40B illustrates the groove reaming tool 4800 following insertionthereof via notch 5000, wherein cutting portions 4888 of cutter elements4880 are still located within acetabulum notch 5000. The groove reamingtool 4800 is also shown fully aligned with axis of symmetry 5006.

FIG. 40C illustrates the groove reaming tool 4800 following applicationof axial downward force, as indicated by an arrow 5007 on handle 4802,causing high friction engagement surface 4862 of end element 4860 tofrictionally engage the reamed acetabulum 5004.

FIG. 40D shows the groove reaming tool 4800 following application ofaxial downward force, as indicated by an arrow 5009 on grip 4806,causing grip 4806 to engage outwardly extendible recess engagementelement 4808 with linear force 5010, thereby forcing the recess on theunderside surface thereof axially against the conical element, asillustrated in FIG. 39B at arrow 4897. This axial force causes radiallyoutward displacement of segments 4818 and causes the high frictionsurface on the outer edge 4822 of segments 4818 into frictionalengagement with the reamed acetabulum 5004, as indicated by arrow 5012.

FIG. 40E shows the groove reaming tool 4800 following an approximately180 degree rotation of handle 4802, groove cutter mounting element 4850and cutter elements 4880 about coaxial axes 5002 and 5006, as indicatedby arrow 5014, thereby producing an approximately 180 degree groove 5016(seen in FIG. 40G) in reamed acetabulum 5004.

FIG. 40F shows the groove reaming tool 4800 following a furtherapproximately 180 degree rotation of handle 4802, groove cutter mountingelement 4850 and cutter elements 4880 about coaxial axes 5002 and 5006,as indicated by arrow 5018, thereby extending groove 5016, producing a360 degree groove in reamed acetabulum 5004.

FIG. 40G illustrates the groove reaming tool 4800 following removalthereof via notch 5000, wherein cutting portions 4888 of cutter elements4880 are still aligned with the acetabulum notch 5000, showing groove5016 produced in the steps described in FIGS. 40E and 40F.

Reference is now made to FIGS. 41A, 41B, 41C and 41D, which aresectional illustrations, showing alternative reamed acetabulumconfigurations.

FIG. 41A illustrates a modification of the machined acetabulum shown inFIG. 40G, wherein a discontinuous groove array 5100 is shown. Thisgroove array is preferably configured to correspond with the protrusionarray shown in FIG. 2A.

FIG. 41B illustrates another modification of the machined acetabulumshown in FIG. 40G, wherein another type of discontinuous recess array5102 is shown. This groove array is preferably configured to correspondwith the protrusion array shown in FIG. 3A.

FIG. 41 illustrates another modification of the machined acetabulumshown in FIG. 40G, wherein a circumferential protrusion 5104 is shown.This circumferential protrusion is preferably configured to correspondwith the circumferential recess shown in FIG. 4A.

FIG. 41D illustrates another modification of the machined acetabulumshown in FIG. 40G, wherein a discontinuous protrusion array 5106 isshown. This discontinuous protrusion array 5106 is preferably configuredto correspond with recess array shown in FIG. 5A.

Reference is now made to FIGS. 42A and 42B, which are simplifiedpictorial illustrations of introduction and pre-snap fit placement of animplantable artificial femoral head resurfacing element adjacent areamed femoral head in accordance with two alternative embodiments ofthe present invention. FIG. 42A shows introduction and placement of animplantable artificial femoral head resurfacing element 5150 adjacent areamed femoral head 5152. Implantable artificial femoral headresurfacing element 5150 may be any suitable implantable artificialfemoral head resurfacing element such as those shown and describedherein, for example, in any of FIGS. 6A-10C.

FIG. 42B shows introduction and placement of a folded implantableartificial femoral head resurfacing element 5160 adjacent a reamedfemoral head 5162. Implantable artificial femoral head resurfacingelement 5160 may be any suitable implantable artificial femoral headresurfacing element such as those shown and described herein. Forexample in any of FIGS. 6A-10C. The embodiment of FIG. 42B isparticularly suitable for minimally invasive surgery.

Reference is now made to FIGS. 43A and 43B, which are simplifiedpictorial illustrations of introduction and pre-snap fit placement of animplantable artificial acetabular socket adjacent a reamed acetabulum inaccordance with two alternative embodiments of the present invention.FIG. 43A shows introduction and placement of an implantable artificialacetabular socket 5170 adjacent a reamed acetabulum 5172. Implantableartificial acetabular socket 5170 may be any suitable implantableartificial acetabular socket such as those shown and described herein,for example in any of FIGS. 1A-5C.

FIG. 43B shows introduction and placement of a folded implantableartificial acetabular socket 5180 adjacent a reamed acetabulum 5182.Implantable artificial acetabular socket 5180 may be any suitableimplantable artificial acetabular socket such as those shown anddescribed herein, for example in any of FIGS. 1A-5C. The embodiment ofFIG. 43B is particularly suitable for minimally invasive surgery.

Reference is now made to FIGS. 44A, 44B, 44C and 44D, which are,respectively, a simplified pictorial illustration and sectionalillustrations of a snap-fit installation of an implantable artificialacetabular socket in a reamed acetabulum in accordance with a preferredembodiment of the present invention. As shown in FIG. 44A, followingintroduction and placement of an implantable artificial acetabularsocket adjacent a reamed acetabulum, a surgeon, using his fingers,gently introduces the artificial acetabular socket into position forsnap-fit engagement with the reamed acetabulum. This position is shownclearly in FIG. 44B, which is a sectional illustration of the reamedacetabulum of FIG. 44A.

For the sake of conciseness and clarity, the implantable artificialacetabular socket 1100 of FIGS. 1A-1C and the description thereof areemployed in the explanation which follows, unless specifically indicatedotherwise. It is appreciated, however, that where suitable, any othertype of acetabular socket described herein may be installed in a manneremploying features described hereinbelow.

At the positioning stage shown in FIGS. 44A and 44B, annular outwardlyextending protrusion 1106 lies in touching, generally non-compressiveengagement with an annular portion 5200 of a generally spherical innerconcave surface 5202 of a machined acetabulum 5204. Annular portion 5200lies above a groove 5206, formed in generally spherical inner concavesurface 5202, which is designed to receive protrusion 1106. Accordingly,engagement of protrusion 1106 with annular portion 5200 causes theimplantable artificial acetabular socket 1100 to rest at a positionwherein an outer edge thereof, designated by reference numeral 5210,lies above a corresponding outer edge 5212 of machined acetabulum 5204.The separation between the planes of outer edge 5210 of implantableartificial acetabular socket 1100 and of outer edge 5212, along axis1101, is indicated by arrows 5214.

As can be seen from FIG. 44B, substantially no stress is applied to theimplantable artificial acetabular socket 1100 and to machined acetabulum5204 by the engagement thereof shown in FIGS. 44A and 44B.

FIG. 44C illustrates a second stage in snap-fit installation of animplantable artificial acetabular socket in a reamed acetabulum inaccordance with a preferred embodiment of the present invention. Asshown in FIG. 44C, following placement of implantable artificialacetabular socket 1100 into position for snap-fit engagement with thereamed acetabulum, as shown in FIGS. 44A and 44B, the surgeon, using hisfingers, gently engages the artificial acetabular socket 1100,preferably at locations, designated by reference numeral 5220, on innerconcave surface 1102 thereof, and presses thereon in a directionindicated by arrows 5222, which direction lies generally along axis1101. The application of this pressure causes displacement of artificialacetabular socket 1100 in direction 5222. Due to the concaveconfiguration of surface 5202 at annular surface portion 5200, thisdisplacement produces radially inward compression of artificialacetabular socket 1100 at protrusion 1106, as indicated by arrows 5224.This radially inward compression results in deformation of theartificial acetabular socket 1100 at protrusion 1106 and in the generalregion thereof, as indicated, inter alia by arrows 5226.

The radially inward compression and the resulting deformation ofartificial acetabular socket 1100 produces stresses in the acetabularsocket 1100, as illustrated, inter alia, by stress contour lines 5231,5232, 5233 and 5234. The above-described engagement of artificialacetabular socket 1100 with the machined acetabulum 5204 causes forcesto be applied to the machined acetabulum 5204, producing compressionstresses therein, as illustrated, inter alia, by stress contour lines5241, 5242, 5243 and 5244, in a region designated by reference numeral5246, in the vicinity of annular surface portion 5200. It is appreciatedthat the stresses thus produced in machined acetabular socket 5204produce corresponding strains therein. Both the stresses and the strainshave positive medical implications, as will be discussed

Displacement of artificial acetabular socket 1100 in direction 5222 isseen to reduce the separation between the planes of outer edge 5210 ofimplantable artificial acetabular socket 1100 and of outer edge 5212along axis 1101, indicated by arrows 5254.

FIG. 44D illustrates a third stage in snap-fit installation of animplantable artificial socket in a reamed acetabulum in accordance witha preferred embodiment of the present invention. As shown in FIG. 44D,the surgeon, using his fingers, presses further on the artificialacetabular socket 1100 preferably at locations, designated by referencenumeral 5220 on inner concave surface 1102 thereof in the directionindicated by arrows 5222. The application of this further pressure,causes further displacement of artificial acetabular socket 1100 indirection 5222. This further displacement produces sliding pressureengagement between underlying surface portion 1110 of protrusion 1106 atthe undercut 1108 and a radially outward extending surface portion 5260of groove 5206. It is noted that the resiliency of the artificialacetabular socket 1100 causes radially outward displacement ofprotrusion 1106, as indicated by arrows 5262. The resulting radiallyoutward decompression results in different deformation of the artificialacetabular socket 1100 at protrusion 1106 and in the general regionthereof, as indicated, inter alia by arrow 5266.

This results in reduced and changed stress patterns in both theartificial acetabular socket 1100 and in the machined acetabulum 5204 atregion 5246 thereof, as indicated by stress contour lines 5271, 5272,5273 and 5274 in artificial acetabular socket 1100 and by stress contourlines 5281, 5282, 5283 and 5284 in machined acetabulum 5204.

The further displacement of artificial acetabular socket 1100 indirection 5122 is seen to further reduce the separation between theplanes of outer edge 5210 of implantable artificial acetabular socket1100 and of outer edge 5212 along axis 1101, indicated by arrows 5294.

Reference is now made to FIGS. 45A and 45B, which are a simplifiedpictorial illustration and sectional illustration of a fourth stage insnap-fit installation of an implantable artificial acetabular socket ina reamed acetabulum in accordance with a preferred embodiment of thepresent invention. As shown in FIG. 45A, the surgeon, using his fingers,now presses on the artificial acetabular socket 1100, preferably atlocations, designated by reference numeral 5300, on edges 5210 thereof,in the direction indicated by arrow 5222.

As seen in FIG. 45B, the application of this further pressure causesfurther displacement of artificial acetabular socket 1100 in direction5222. This further displacement produces sliding snap-fit engagementbetween protrusion 1106 and groove 5206.

It is noted that the resiliency of the artificial acetabular socket 1100causes radially outward displacement of protrusion 1106, as indicated byarrows 5302. The resulting radially outward decompression generallyeliminates deformation of the artificial acetabular socket 1100 atprotrusion 1106 and in the general region thereof designated byreference numeral 5220.

It is noted that the snap-fit engagement shown in FIG. 45B is agenerally non-press fit engagement. Touching engagement between theartificial acetabular socket 1100 and the machined acetabulum 5204typically takes place at surface 1104 of artificial acetabular socket1100 and surface 5202 of the machined acetabulum. Accordingly thestresses in both the acetabular socket 1100 and in the machinedacetabulum 5204 are generally small and localized in the region of thesnap fit engagement therebetween, as indicated by stress contour lines5311 and 5312 in artificial acetabular socket 1100 and by stress contourlines 5321 and 5322 in machined acetabulum 5204.

It is also appreciated that the snap-fit engagement of the artificialacetabular socket 1100 with the machined acetabulum 5204 produceslocking of the artificial acetabular socket 1100 in groove 5206, whereinundercut 1108 prevents disengagement of protrusion 1106 from groove5206.

Reference is now made to FIGS. 46A, 46B, 46C and 46D, which areillustrations of an implantable artificial acetabular socket,constructed and operative in accordance with a further preferredembodiment of the present invention, which is particularly suitable foruse in a hip joint.

As seen in FIGS. 46A, 46B, 46C and 46D, an implantable artificialacetabular socket, designated by reference numeral 5600, is formedpreferably by injection molding of polyurethane. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial acetabular socket 5600 is of anuneven thickness, and defines a concave hemispherical inner articulationsurface 5602 which is symmetric about an axis 5601, having a bevelededge 5603, and a generally hemispherical outer bone engagement surface5604 which preferably has formed thereon at any suitable locationbetween its apex and its rim a generally annular outwardly extendingprotrusion 5606, preferably defining a generally annular undercut 5608.Alternatively, the protrusion 5606 may be any other suitablenon-annular, open or closed, generally peripheral, protrusion. Theprotrusion 5606 is preferably arranged for snap-fit engagement with acorresponding groove formed by reaming of a bone, examples of which aredescribed hereinabove.

Preferably, the protrusion 5606 has a cross-sectional configuration, ascan be readily seen in FIG. 46B, which is characterized in that anunderlying surface portion 5610 of protrusion 5606, at the undercut5608, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 5612 of protrusion 5606.

It is a particular feature of the implantable artificial acetabularsocket 5600 that its thickness varies at various regions, correspondingto various portions of the bone engagement surface 5604, which gives itan asymmetric configuration requiring a definition of the implantingorientation with regard to the acetabulum. Preferably, a marking 5620,such as a writing “notch” corresponding to the acetabulum notch, is usedto position implantable artificial acetabular socket 5600 in itsdesigned orientation placing the marking 5620 at the acetabulum notch.

Preferably, implantable artificial acetabular socket 5600 defines anuneven thickness portion 5626 between its apex and the annular outwardlyextending protrusion 5606. Alternatively, other uneven thicknessportions may be defined, such as a protrusion similar to protrusion 5606constructed of a varied cross section. Alternatively, the portiondefined between annular outwardly extending protrusion 5606 and the rimmay be of an uneven thickness.

As seen in FIG. 46B, which is a sectional illustration taken along linesXLVIB-XLVIB of FIG. 46A, preferably, uneven thickness portion 5626includes a region 5628 of a thickness less than the average thickness ofuneven thickness portion 5626, which is located opposite marking 5620,which is at the bottom part of implantable artificial acetabular socket5600, and a region 5630 of a thickness greater than the averagethickness of uneven thickness portion 5626, located towards marking 5620at the bottom part of the implantable artificial acetabular socket 5600.

As seen in FIG. 46C, which is a sectional illustration taken along linesXLVIC-XLVIC of FIG. 46A, uneven thickness portion 5626 may include othervariations of thickness across uneven thickness portion 5626.

Reference is now made to FIGS. 47A, 47B and 47C, which are illustrationsof an implantable artificial acetabular socket constructed and operativein accordance with another preferred embodiment of the presentinvention, which is particularly suitable for use in a hip joint.

As seen in FIGS. 47A, 47B and 47C, an implantable artificial acetabularsocket, designated by reference numeral 5640, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 5640 is ofgenerally uniform thickness, is symmetric about an axis 5641 and definesan hemispherical concave inner articulation surface 5642, having abeveled edge 5643, and a generally hemispherical outer bone engagementsurface 5644 which preferably has formed thereon at any suitablelocation between its apex and its rim a generally annular outwardlyextending protrusion 5646, preferably defining a generally annularundercut 5648. Alternatively, the protrusion 5646 may be any othersuitable non-annular, open or closed, generally peripheral, protrusion.The protrusion 5646 is preferably arranged for snap-fit engagement witha corresponding groove formed by reaming of a bone, examples of whichare described hereinabove.

Preferably, the protrusion 5646 has a cross-sectional configuration, ascan be readily seen in FIG. 47B, which is characterized in that anunderlying surface portion 5650 of protrusion 5646, at the undercut5648, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 5652 of protrusion 5646.

Implantable artificial acetabular socket 5640 is constructed from anouter layer 5662, all intermediate layer 5664, preferably, including aplurality of voids 5666, and an inner layer 5668. Outer layer 5662 ispreferably molded of a polyurethane of durometer number 55 shore D,intermediate layer 5664 is preferably molded of a polyurethane ofdurometer number 70 shore D, and inner layer 5668 is preferably moldedof a polyurethane of durometer number 80 shore A. Intermediate layer5664 preferably includes carbon whiskers.

In another preferred embodiment of the present invention, implantableartificial acetabular socket 5640 is constructed from an outer layer5662, an intermediate layer 5664, preferably, including a plurality ofvoids 5666, and an inner layer 5668. Outer layer 5662 is preferablymolded of a polyurethane of durometer number 55 shore D, inner layer5668 is preferably molded of a polyurethane of durometer number 80 shoreA and intermediate layer 5664 is preferably molded of a polyurethanehaving a fluid absorption property, such as HydroThaneTM, manufacturedby CardioTech International, Inc. 78E Olympia Ave., Woburn, Mass., USA.Inner layer 5668 has formed in articulation surface 5642 a plurality ofthoroughgoing apertures 5670 connecting to voids 5666.

Reference is now made to FIGS. 48A, 48B, 48C and 48D which are partiallycut away pictorial illustrations of an implantable artificial acetabularsocket constructed and operative in accordance with still anotherpreferred embodiment of the present invention and which is particularlysuitable for use in a hip joint.

As seen in FIGS. 48A, 48B, 48C and 48D, an implantable artificialacetabular socket, designated by reference numeral 5680, is formedpreferably by injection molding of polyurethane. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial acetabular socket 5680 is ofgenerally uniform thickness, is symmetric about an axis 5681 and definesan hemispherical concave inner articulation surface 5682, having abeveled edge 5683, and a generally hemispherical outer bone engagementsurface 5684 which preferably has formed thereon at any suitablelocation between its apex and its rim a generally annular outwardlyextending protrusion 5686, preferably defining a generally annularundercut 5688. Alternatively, the protrusion 5686 may be any othersuitable non-annular, open or closed, generally peripheral, protrusion.The protrusion 5686 is preferably arranged for snap-fit engagement witha corresponding groove formed by reaming of a bone, examples of whichare described hereinabove.

Preferably, the protrusion 5686 has a cross-sectional configuration,which is characterized in that an underlying surface portion 5690 ofprotrusion 5686, at the undercut 5688, defines a slope which is sharperthan a corresponding slope of an overlying surface portion 5692 ofprotrusion 5686.

Implantable artificial acetabular socket 5680 is constructed from anouter layer 5702, as shown in FIG. 48B, and an inner layer 5704, asshown in FIG. 48D, and includes an inserted internal deformation controlelement 5706, as shown in FIG. 48C. Outer layer 5702 is preferablymolded of a polyurethane of durometer number 55 shore D and inner layer5704 is preferably molded of a polyurethane having a durometer number 80shore A. Internal deformation control element 5706 is preferably moldedof a relatively rigid polyurethane, typically one having a Shorehardness of approximately 70D and may have carbon whiskers embeddedtherein. The deformation control element 5706 preferably has an overallgenerally annular configuration, defined by a web portion 5712, a firstthickened portion 5714, having a circular cross section, and a secondthickened portion 5716 having a rectangular cross section.

Preferably, deformation control element 5706 is configured andinsertably positioned within implantable artificial acetabular socket5680 with portions of outer layer 5702 covering it outwardly and withportions of inner layer 5704 covering it inwardly.

Reference is now made to FIGS. 49A and 49B, which are respectivepictorial and partially cut away illustrations of an implantableartificial acetabular socket, constructed and operative in accordancewith still another preferred embodiment of the present invention, whichis particularly suitable for use in a hip joint.

As seen in FIGS. 49A and 49B, an implantable artificial acetabularsocket, designated by reference numeral 5750, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 5750 is ofgenerally uniform thickness, is symmetric about an axis 5751 and definesan hemispherical concave inner articulation surface 5752, having abeveled edge 5753, and a generally hemispherical outer bone engagementsurface 5754 which preferably has formed thereon at any suitablelocation between its apex and its rim a generally annular outwardlyextending protrusion 5756, preferably defining a generally annularundercut 5758. Alternatively, the protrusion 5756 may be any othersuitable non-annular, open or closed, generally peripheral protrusion.The protrusion 5756 is preferably arranged for snap-fit engagement witha corresponding groove formed by reaming of a bone, examples of whichare described hereinabove.

Preferably, the protrusion 5756 has a cross-sectional configuration,which is characterized in that an underlying surface portion 5760 ofprotrusion 5756, at the undercut 5758, defines a slope which is sharperthan a corresponding slope of an overlying surface portion 5762 ofprotrusion 5756.

It is a particular feature of the artificial implantable artificialacetabular socket 5750 that it is constructed from a single layer,preferably, molded of a polyurethane of durometer number 80 shore A, andincludes an inserted internal deformation control element 5776,illustrated pictorially in FIG. 49B. The deformation control element5776 is preferably molded of a relatively rigid polyurethane, typicallyone having a Shore hardness of approximately 70D, and may have carbonwhiskers embedded therein.

Preferably, deformation control element 5776 is configured andinsertably positioned within implantable artificial acetabular socket5750 with portions of PU material of the single molded layer covering itoutwardly, inwardly and towards the rim of implantable artificialacetabular socket 5750.

The deformation control element 5776 preferably has an overall generallyannular configuration defined by a web portion 5782, a first thickenedportion 5784, having a circular cross section, and a second thickenedportion 5786, having a circular cross section. Deformation controlelement 5776 is further defined by rectangular cut-outs 5792 separatedby flaps 5794 which terminate in thickened portions 5784 which are alsoseparated by cut-outs 5792.

Reference is now made to FIGS. 50A and 50B, which are respectivepictorial and partially cut away illustrations of an implantableartificial acetabular socket, constructed and operative in accordancewith still another preferred embodiment of the present invention, whichis particularly suitable for use in a hip joint.

As seen in FIGS. 50A and 50B, an implantable artificial acetabularsocket, designated by reference numeral 5800, is formed preferably byinjection molding of polyurethane over a reinforcing deformation controlelement. Preferred polyurethane materials are described hereinbelow.

Preferably, implantable artificial acetabular socket 5800 is ofgenerally uniform thickness, is symmetric about an axis 5801 and definesan hemispherical concave inner articulation surface 5802, having abeveled edge 5803, and a generally hemispherical outer bone engagementsurface 5804 which preferably has formed thereon at any suitablelocation between its apex and its rim a generally annular outwardlyextending protrusion 5806, preferably defining a generally annularundercut 5808. Alternatively, the protrusion 5806 may be any othersuitable non-annular, open or closed, generally peripheral, protrusion.The protrusion 5806 is preferably arranged for snap-fit engagement witha corresponding groove formed by reaming of a bone, examples of whichare described hereinabove.

Preferably, the protrusion 5806 has a cross-sectional configuration, ascan be readily seen in FIG. 50A, which is characterized in that anunderlying surface portion 5810 of protrusion 5806, at the undercut5808, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 5812 of protrusion 5806.

Implantable artificial acetabular socket 5800 is constructed from asingle layer, preferably, molded of a polyurethane of durometer number80 shore A over internal deformation control element 5826, illustratedpictorially in FIG. 50B. The deformation control element 5826 ispreferably formed of woven high performance fibers, such as carbonfibers, KEVLAR®, DYNEEMA®, and glass fibers, and has an overallgenerally truncated spherical configuration defined by arched cut-outs5836 separated by flaps 5838 which terminate in transverse cylindricalportions 5840 in which are fixedly disposed rigid rod element 5842 whichextends circumferentially as an open or closed ring.

It is seen that deformation control element 5826 is preferably moldedentirely within artificial implantable artificial acetabular socket5800.

Reference is now made to FIGS. 51A, 51B and 51C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial femoral head resurfacing, element constructed andoperative in accordance with a further preferred embodiment of thepresent invention. The implantable artificial femoral head resurfacingelement is intended for mounting onto a natural femoral head inaccordance with a preferred embodiment of the present invention.

As seen in FIGS. 51A, 51B and 51C, an implantable artificial femoralhead resurfacing element, designated by reference numeral 5850, isformed preferably by injection molding, of polyurethane. Preferredpolyurethane materials are described hereinbelow.

Preferably, implantable artificial femoral head resurfacing element 5850is of generally uneven thickness, with a distinct thickened portion atits apex. Artificial femoral head resurfacing element 5850 defines ahemispherical outer articulation surface 5852 and an inner boneengagement surface 5854, having a beveled edge 5855, which preferablyhas formed thereon at any suitable location between its apex and its rima generally annular inwardly extending protrusion 5856, preferablydefining a generally annular undercut 5858. Alternatively, theprotrusion 5856 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The protrusion 5856 is preferablyarranged for snap-fit engagement with a corresponding groove formed byreaming of a femoral head.

Preferably, the protrusion 5856 has a cross-sectional configuration, ascan be readily seen in FIG. 51B, which is characterized in that anunderlying surface portion 5860 of protrusion 5856, at the undercut5858, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 5862 of protrusion 5856.

Implantable artificial femoral head resurfacing element 5850 defines anuneven thickness portion 5876 extending between thickened apex portionand the protrusion 5856. The thickness of uneven thickness portion 5876varies at various regions, corresponding to various portions of the boneengagement surface 5854, which renders it an asymmetric configurationrequiring a definition of the implanting orientation with regard to thefemoral head. Preferably, a marking numeral 5870, such as the writingtrochanter, designating and corresponding to the great trochanter, isused to position implantable artificial femoral head resurfacing element5850 in its designed orientation by placing the marking 5870 facing thegreat trochanter.

As can be seen in FIG. 51B, preferably, uneven thickness portion 5876comprises a region 5878 of a thickness less than the average thicknessof uneven thickness portion 5876, located facing marking 5870, and aregion 5880 of a thickness greater than the average thickness of uneventhickness portion 5876, located away from marking 5870.

As can be seen in FIG. 51C, preferably, uneven thickness portion 5876may include other variations of thickness across uneven thicknessportion 5876.

Reference is now made to FIGS. 52A, 52B and 52C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial femoral head resurfacing element constructed andoperative in accordance with another preferred embodiment of the presentinvention.

As seen in FIGS. 52A, 52B, and 52C, an implantable artificial femoralhead resurfacing element, designated by reference numeral 5900, isformed preferably by injection molding of multi layers of polyurethaneincluding a fluid absorbing layer. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial femoral head resurfacing element 5900is of generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 5901 and defines an hemisphericalouter articulation surface 5902 and a generally hemispherical inner boneengagement surface 5904, having a beveled edge 5905, which preferablyhas formed thereon at any suitable location between its apex and its rima generally annular inwardly extending protrusion 5906, preferablydefining a generally annular undercut 5908. Alternatively, theprotrusion 5906 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The protrusion 5906 is preferablyarranged for snap-fit engagement with a corresponding groove formed byreaming of a femoral head.

Preferably, the protrusion 5906 has a cross-sectional configuration, ascan be readily seen in FIG. 52B, which is characterized in that anunderlying surface portion 5910 of protrusion 5906, at the undercut5908, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 5912 of protrusion 5906.

Implantable artificial femoral head resurfacing element 5900 isconstructed from an inner layer 5922, an intermediate layer 5924, whichpreferably includes a plurality of voids 5926, and an outer layer 5928.Inner layer 5922 is, preferably, molded of a polyurethane of durometernumber 55 shore D, outer layer 5928 is, preferably, molded of apolyurethane of durometer number 80 shore A and intermediate layer 5924is, preferably, molded of a polyurethane having a fluid absorptionproperty, such as HydroThaneTM, manufactured by CardioTechInternational, Inc., 78E Olympia Ave., Woburn, Mass., USA. Outer layer5928 has formed in articulation surface 5902 a plurality ofthoroughgoing apertures 5929 connecting to voids 5926.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial femoral head resurfacingelement 5900 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 53A, 53B and 53C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial femoral head resurfacing element, intended formounting onto a natural femoral head, in accordance with still anotherpreferred embodiment of the present invention.

As seen in FIGS. 53A, 53B, and 53C, an implantable artificial femoralhead resurfacing element, designated by reference numeral 5950, isformed preferably by injection molding of polyurethane formed over adeformation control element. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial femoral head resurfacing element 5950is of generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 5951 and defines an hemisphericalouter articulation surface 5952 and a generally hemispherical inner boneengagement surface 5954, having a beveled edge 5955, which preferablyhas formed thereon at any suitable location between its apex and its rima generally annular inwardly extending protrusion 5956, preferablydefining a generally annular undercut 5958. Alternatively, theprotrusion 5956 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The protrusion 5956 is preferablyarranged for snap-fit engagement with a corresponding groove formed byreaming of a femoral head.

Preferably, the protrusion 5956 has a cross-sectional configuration, ascan be readily seen in FIG. 53B, which is characterized in that anunderlying surface portion 5960 of protrusion 5956, at the undercut5958, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 5962 of protrusion 5956.

Implantable artificial femoral head resurfacing element 5950 isconstructed from a single layer molded of a polyurethane of durometernumber 80 shore A, and includes an inserted array 5964 of internaldeformation control elements 5966, as seen in FIG. 53C. The deformationcontrol elements 5966 are preferably molded of a relatively rigidpolyurethane, typically one having a Shore hardness of approximately 70Dand maw have carbon whiskers embedded therein.

The deformation control elements 5966, preferably, have an overallgenerally partial annular configuration including a web portion 5968, afirst thickened portion 5970, having, a circular cross section, and asecond thickened portion 5972 having a rectangular cross section.Preferably, deformation control elements 5966 are configured andinsertably positioned within implantable artificial femoral headresurfacing element 5950 with portions of PU material of the singlemolded layer covering them outwardly, inwardly and towards the rim ofimplantable artificial femoral head resurfacing element 5950.

Reference is now made to FIGS. 54A, 54B and 54C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial femoral head resurfacing element, intended formounting onto a natural femoral head, in accordance with yet anotherpreferred embodiment of the present invention.

As seen in FIGS. 54A, 54B, and 54C, an implantable artificial femoralhead resurfacing element, designated by reference numeral 6000, isformed preferably by injection molding of multi layers of polyurethaneformed over a deformation control element. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial femoral head resurfacing element 6000is of generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 6001 and defines an hemisphericalouter articulation surface 6002 and a generally hemispherical inner boneengagement surface 6004, having a beveled edge 6005, which preferablyhas formed thereon at any suitable location between its apex and its rima generally annular inwardly extending protrusion 6006, preferablydefining a generally annular undercut 6008. Alternatively, theprotrusion 6006 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The protrusion 6006 is preferablyarranged for snap-fit engagement with a corresponding groove formed byreaming of a femoral head.

Preferably, the protrusion 6006 has a cross-sectional configuration, ascan be readily seen in FIG. 54B, which is characterized in that anunderlying surface portion 6010 of protrusion 6006, at the undercut6008, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 6012 of protrusion 6006.

Implantable artificial femoral head resurfacing element 6000 isconstructed from an outer layer 6022 and an inner layer 6024 andincludes an inserted array 6026 of internal deformation control elements6028, as seen in FIG. 54C. Outer layer 6022 is, preferably, molded of apolyurethane of durometer number 80 shore A, and inner layer 6024 is,preferably, molded of a polyurethane having a durometer number 55 shoreD. The deformation control elements 6028 are preferably molded of arelatively rigid polyurethane, typically one having a Shore hardness ofapproximately 70D and may have carbon whiskers embedded therein.

The deformation control elements 6028 preferably have an overallgenerally partial annular configuration including a web portion 6032, afirst thickened portion 6034, having a circular cross section, and asecond thickened portion 6036, having a rectangular cross section.Preferably, deformation control elements 6028 are configured andinsertably positioned within implantable artificial femoral headresurfacing element 6000 with portions of outer layer 6022 covering themoutwardly and with portions of inner layer 6024 covering them inwardlyand towards the rim of implantable artificial femoral head resurfacingelement 6000.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial femoral head resurfacingelement 6000 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 55A, 55B and 55C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial femoral head resurfacing element constructed andoperative in accordance with a further preferred embodiment of thepresent invention. The implantable artificial femoral head resurfacingelement is intended for mounting onto a natural femoral head inaccordance with a preferred embodiment of the present invention.

As seen in FIGS. 55A, 55B and 55C, an implantable artificial femoralhead resurfacing element, designated by reference numeral 6100, isformed preferably by injection moldings of polyurethane over areinforcing deformation control element. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial femoral head resurfacing element 6100is of generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 6101 and defines an hemisphericalouter articulation surface 6102 and a generally hemispherical inner boneengagement surface 6104, having a beveled edge 6105, which preferablyhas formed thereon, at any suitable location between its apex and itsrim, a generally annular inwardly extending protrusion 6106, preferablydefining a generally annular undercut 6108. Alternatively, theprotrusion 6106 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The protrusion 6106 is preferablyarranged for snap-fit engagement with a corresponding groove formed byreaming of a femoral head.

Preferably, the protrusion 6106 has a cross-sectional configuration, ascan be readily seen in FIG. 55B, which is characterized in that anunderlying surface portion 6110 of protrusion 6106, at the undercut6108, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 6112 of protrusion 6106.

It is a particular feature of the artificial femoral head resurfacingelement 6100 that it includes an internal reinforcing deformationcontrol element, which is designated by reference numeral 6114 andillustrated pictorially in FIG. 55C. The deformation control element6114 is preferably formed of woven high performance fibers, such ascarbon fibers, KEVLAR®, DYNEEMA®, and glass fibers, and has an overallgenerally truncated spherical configuration defined by arched cut-outs6116 separated by flaps 6118 which terminate in transverse cylindricalportions 6120 in which are fixedly disposed rigid rod elements 6122,ends 6124 of which extend beyond flaps 6118, as shown.

It is seen that insert 6114 is preferably molded entirely withinartificial femoral head resurfacing element 6100.

Reference is now made to FIGS. 56A, 56B and 56C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a further preferred embodiment of the present inventionand which is particularly suitable for use in a hip joint.

As seen in FIGS. 56A, 56B and 56C, an implantable artificial acetabularsocket, designated by reference numeral 6200, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 6200 comprises asurface of rotation which is symmetric about an axis 6201 and defines agenerally hemispherical outer bone engagement surface 6204 whichpreferably has formed thereon, at any suitable location between its apexand its rim, a generally annular outwardly extending protrusion 6206,preferably defining a generally annular undercut 6208. Alternatively,the protrusion 6206 may be any other suitable non-annular, open orclosed, generally peripheral, protrusion. The protrusion 6206 ispreferably arranged for snap-fit engagement with a corresponding grooveformed by reaming of a bone, examples of which are describedhereinabove.

Preferably, the protrusion 6206 has a cross-sectional configuration, ascan be readily seen in FIG. 56B, which is characterized in that anunderlying surface portion 6210 of protrusion 6206, at the undercut6208, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 6212 of protrusion 6206.

It is a particular feature of the implantable artificial acetabularsocket 6200 that an inner surface thereof defines two portions ofspherical surfaces of rotation having different radii. A first portion,designated by reference numeral 6214, having a radius designated byreference numeral 6216, extends from a beveled edge 6218 to a peripheralstep 6220. A second portion, designated by reference numeral 6224, andhaving a radius designated by reference numeral 6226, which radius islarger than radius 6216, extends from step 6220 to the apex, heredesignated by reference numeral 6228.

It is appreciated that surface 6224 need not be spherical, provided thatit does not extend to a location within the spherical volume partiallydefined by surface portion 6214 and thus defines a recess extendingbeyond that spherical volume.

Reference is now made to FIGS. 57A, 57B and 57C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a further preferred embodiment of the present inventionand which is particularly suitable for use in a hip joint.

As seen in FIGS. 57A, 57B and 57C, an implantable artificial acetabularsocket, designated by reference numeral 6350, is formed preferably byinjection molding or polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 6350 comprises asurface of rotation which is symmetric about an axis 6351 and defines agenerally hemispherical outer bone engagement surface 6354 whichpreferably has formed thereon, at any suitable location between its apexand its rim, a generally annular outwardly extending protrusion 6356,preferably defining a generally annular undercut 6358. Alternatively,the protrusion 6356 may be any other suitable non-annular, open orclosed generally peripheral, protrusion. The protrusion 6356 ispreferably arranged for snap-fit engagement with a corresponding grooveformed by reaming of a bone, examples of which are describedhereinabove.

Preferably, the protrusion 6356 has a cross-sectional configuration, ascan be readily seen in FIG. 57B, which is characterized in that anunderlying surface portion 6360 of protrusion 6356, at the undercut6358, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 6362 of protrusion 6356.

Artificial acetabular socket 6350 is similar to artificial acetabularsocket 1100 shown is FIGS. 1A-1C, except that an inner articulationsurface 6364 defines an additional hemispherical concave layer 6366along a portion thereof. Additional concave layer 6366 is defined by aperipheral step 6370 and extends from peripheral step 6370 to the apex6372 of acetabular socket 6350. Additional concave layer 6366 alsocontinues below peripheral step 6370, underlying a portion of innersurface 6364 and continuing until a lower edge 6374, and defines arecess provided to allow for the accumulation of synovial fluid forlubrication of the articulation surface 6364.

It is appreciated that the provision of layer 6366 further defines innerarticulation surface 6364 as having a horseshoe shaped portion to moreclosely approximate the acetabular articular surface of the naturalacetabulum. This provides for an articulation surface that more closelyapproximates the natural articulation surface.

Reference is now made to FIGS. 58A and 58B, which are respectivepartially cut away pictorial and sectional illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a further preferred embodiment of the present inventionand which is particularly suitable for use in a hip joint.

As seen in FIGS. 58A and 58B, an implantable artificial acetabularsocket, designated by reference numeral 7100, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 7100 is ofgenerally uniform thickness, is symmetric about an axis 7101 and definesan hemispherical concave inner articulation surface 7102, having abeveled edge 7103, and a generally hemispherical outer bone engagementsurface 7104, which preferably has formed thereon, at any suitablelocation between its apex and its rim, a generally annular outwardlyextending protrusion 7106, preferably defining a generally annularundercut 7108. Alternatively, the protrusion 7106 may be any othersuitable non-annular, open or closed, generally peripheral, protrusion.The protrusion 7106 is preferably arranged for snap-fit engagement witha corresponding groove formed by reaming of a bone, examples of whichare described hereinabove.

Preferably, the protrusion 7106 has a cross-sectional configuration, ascan be readily seen in FIG. 58B, which is characterized in that anunderlying surface portion 7110 of protrusion 7106, at the undercut7108, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 7112 of protrusion 7106.

Artificial acetabular socket 7100 is similar to artificial acetabularsocket 1100 shown is FIGS. 1A-1C, except that inner articulation surface7102 is further defined by a hexagonal configuration pattern, whichincludes hexagonal recessed surface portions 7120. Recessed surfaceportions 7120 may be connected or isolated from each other and areprovided to allow for the accumulation of synovial fluid for lubricationof the articulation surface 7102. Additionally, the hexagonal recessedconfiguration provides for reduced surface contact area, which reducesfriction. It is appreciated that, even though the illustrated embodimentshows a hexagonal configuration, any suitable configuration of recessedsurface portions may be provided.

Reference is now made to FIGS. 59A and 59B, which are respectivepartially cut away pictorial and sectional illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a further preferred embodiment of the present inventionand which is particularly suitable for use in a hip joint.

As seen in FIGS. 59A and 59B, an implantable artificial acetabularsocket, designated by reference numeral 7150, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 7150 is ofgenerally uniform thickness, is symmetric about an axis 7151 and definesan hemispherical concave inner articulation surface 7152, having abeveled edge 7153, and a generally hemispherical outer bone engagementsurface 7154, which preferably has formed thereon, at any suitablelocation between its apex and its rim, a generally annular outwardlyextending protrusion 7156, preferably defining a generally annularundercut 7158. Alternatively, the protrusion 7156 may be any othersuitable non-annular, open or closed, generally peripheral, protrusion.The protrusion 7156 is preferably arranged for snap-fit engagement witha corresponding groove formed by reaming of a bone, examples of whichare described hereinabove.

Preferably, the protrusion 7156 has a cross-sectional configuration, ascan be readily seen in FIG. 59B, which is characterized in that anunderlying surface portion 7160 of protrusion 7156, at the undercut7158, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 7162 of protrusion 7156.

Artificial acetabular socket 7150 is similar to artificial acetabularsocket 7100 shown is FIGS. 55A-58B, except that inner surface 7152 isfurther defined by a hexagonal configuration pattern, which includeshexagonal recessed surface portions 7170 connected by peripheralchannels 7174. Peripheral channels 7174 are preferably interconnectedand continuous and are provided to allow synovial fluid to pass throughfor lubrication of the articulation surface 7152. Additionally, thehexagonal recessed configuration provides for reduced surface contactarea, which reduces friction. It is appreciated that, even though theillustrated embodiment shows a hexagonal configuration, any suitableconfiguration of recessed surface portions may be provided.

Reference is now made to FIGS. 60A, 60B and 60C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a further preferred embodiment of the present inventionand which is particularly suitable for use in a hip joint.

As seen in FIGS. 60A, 60B and 60C, an implantable artificial acetabularsocket, designated by reference numeral 7200, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 7200 is ofgenerally uniform thickness, is symmetric about an axis 7201 and definesan hemispherical concave inner articulation surface 7202, having abeveled edge 7203, and a generally hemispherical outer bone engagementsurface 7204 which preferably has formed thereon, at any suitablelocation between its apex and its rim, a generally annular outwardlyextending protrusion 7206, preferably defining a generally annularundercut 7208. Alternatively, the protrusion 7206 may be any othersuitable non-annular, open or closed, generally peripheral, protrusion.The protrusion 7206 is preferably arranged for snap-fit engagement witha corresponding groove formed by reaming of a bone, examples of whichare described hereinabove.

Preferably, the protrusion 7206 has a cross-sectional configuration, ascan be readily seen in FIG. 60B, which is characterized in that anunderlying surface portion 7210 of protrusion 7206, at the undercut7208, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 7212 of protrusion 7206.

It is a particular feature of the implantable artificial acetabularsocket 7200 that it includes an internal reinforcing deformation controlelement, which is designated by reference numeral 7214 and illustratedpictorially in FIG. 60C. The deformation control element 7214 ispreferably molded of a relatively rigid polyurethane, typically onehaving a Shore hardness of approximately 70D and may have carbonwhiskers embedded therein. The deformation control element 7214preferably has an overall generally truncated spherical configurationdefined by rectangular cut-outs 7216 separated by flaps 7218 whichterminate in thickened portions 7220. It is seen that deformationcontrol element 7214 is preferably molded entirely within artificialacetabular socket 7200.

Reference is now made to FIGS. 61A, 61B and 61C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial femoral head resurfacing element constructed andoperative in accordance with a further preferred embodiment of thepresent invention. The implantable artificial femoral head resurfacingelement is intended for mounting, onto a natural femoral head inaccordance with a preferred embodiment of the present invention.

As seen in FIGS. 61A, 61B and 61C, an implantable artificial femoralhead resurfacing element, designated by reference numeral 7250, isformed preferably by injection molding of polyurethane. Preferredpolyurethane materials are described hereinbelow.

Preferably, implantable artificial femoral head resurfacing element 7250is of generally uneven thickness, with a distinct thickened portion atits apex. Artificial femoral head resurfacing element 7250 defines ahemispherical outer articulation surface 7252 and an inner boneengagement surface 7254, having a beveled edge 7255, which preferablyhas formed thereon at any suitable location between its apex and its rima generally annular inwardly extending protrusion 7256, preferablydefining a generally annular undercut 7258. Alternatively, theprotrusion 7256 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The protrusion 7256 is preferablyarranged for snap-fit engagement with a corresponding groove formed byreaming of a femoral head.

Preferably, the protrusion 7256 has a cross-sectional configuration, ascan be readily seen in FIG. 61B, which is characterized in that anunderlying surface portion 7260 of protrusion 7256, at the undercut7258, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 7262 of protrusion 7256.

It is a particular feature of the implantable artificial femoral headresurfacing element 7250 that outer articulation surface 7252 furtherdefines two portions of spherical surfaces of rotation. A first portion,designated by reference numeral 7264, extends from beveled edge 7255 toa generally circular rim 7270. A second portion, designated by referencenumeral 7274, extends from rim 7270 to the apex, here designated byreference numeral 7278. As seen in FIG. 61A, rim 7270 is not at auniform distance from beveled edge 7255. The provision of rim 7270allows artificial femoral head resurfacing element 7250 to more closelyapproximate a natural femoral head, which reduces friction and providesa thicker portion aligned with the area of greatest stress applied tothe surface element during articulation. It is appreciated that, eventhough, in the illustrated embodiment of FIGS. 61A-61C, rim 7270 iscircular, any suitable configuration of rim 7270, may be provided. Onesuch alternate configuration of rim 7270 is shown hereinbelow in FIGS.62A-62C.

As shown in FIGS. 61A-61C, artificial femoral head resurfacing element7250 need not have a uniform outer articulation surface, but isthickened asymmetrically to provide a thicker portion where required bythe specific joint reaction force of the joint with which it isarticulating.

Reference is now made to FIGS. 62A, 62B and 62C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial femoral head resurfacing element constructed andoperative in accordance with a further preferred embodiment of thepresent invention. The implantable artificial femoral head resurfacingelement is intended for mounting onto a natural femoral head inaccordance with a preferred embodiment of the present invention.

As seen in FIGS. 62A, 62B and 62C, an implantable artificial femoralhead resurfacing element, designated by reference numeral 7300, isformed preferably by injection molding of polyurethane. Preferredpolyurethane materials are described hereinbelow.

Preferably, implantable artificial femoral head resurfacing element 7300is of generally uneven thickness, with a distinct thickened portion atits apex. Artificial femoral head resurfacing element 7300 defines ahemispherical outer articulation surface 7302 and an inner boneengagement surface 7304, having a beveled edge 7305, which preferablyhas formed thereon at any suitable location between its apex and its rima generally annular inwardly extending protrusion 7306, preferablydefining a generally annular undercut 7308. Alternatively, theprotrusion 7306 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The protrusion 7306 is preferablyarranged for snap-fit engagement with a corresponding groove formed byreaming of a femoral head.

Preferably, the protrusion 7306 has a cross-sectional configuration, ascan be readily seen in FIG. 62B, which is characterized in that anunderlying surface portion 7310 of protrusion 7306, at the undercut7308, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 7312 of protrusion 7306.

It is a particular feature of the implantable artificial femoral headresurfacing element 7300 that outer articulation surface 7302 furtherdefines two portions of spherical surfaces of rotation. A first portion,designated by reference numeral 7314, extends from beveled edge 7305 toa rim 7320. A second portion, designated by reference numeral 7324,extends from rim 7320 to the apex, here designated by reference numeral7328. As seen in FIG. 62A, rim 7320 is not at a uniform distance frombeveled edge 7305. The provision of rim 7320 allows artificial femoralhead resurfacing element 7300 to more closely approximate a naturalfemoral head, which reduces friction and provides a thicker portionaligned with the area of greatest stress applied to the surface elementduring articulation.

As shown in FIGS. 62A-62C, artificial femoral head resurfacing element7300 need not have a uniform outer articulation surface, but isthickened asymmetrically to provide a thicker portion where required bythe specific joint reaction force of the joint with which it isarticulating.

Reference is now made to FIGS. 63A and 63B, which are respectivepictorial and sectional illustrations of an implantable artificialfemoral or humeral head resurfacing element constructed and operative inaccordance with still another preferred embodiment of the presentinvention. The implantable artificial femoral or humeral headresurfacing element is intended for mounting onto a natural femoral orhumeral head in accordance with a preferred embodiment of the presentinvention.

As seen in FIGS. 63A and 63B, an implantable artificial femoral orhumeral head resurfacing element, designated by reference numeral 7400,is formed preferably by injection molding of polyurethane. Preferredpolyurethane materials are described hereinbelow.

Preferably, implantable artificial femoral or humeral head resurfacingelement 7400 is of generally uniform thickness, other than at its apexwhich is thickened, is symmetric about an axis 7401 and defines anhemispherical outer articulation surface 7402 and a generallyhemispherical inner bone engagement surface 7404, having a beveled edge7405, which preferably has formed thereon, at any suitable locationbetween its apex and its rim, a generally annular inwardly extendingprotrusion 7406, preferably defining a generally annular undercut 7408.Alternatively, the protrusion 7406 may be any other suitablenon-annular, open or closed, generally peripheral, protrusion. Theprotrusion 7406 is preferably arranged for snap-fit engagement with acorresponding groove formed by reaming of a femoral or humeral head.

Preferably, the protrusion 7406 has a cross-sectional configuration, ascan be readily seen in FIG. 63B, which is characterized in that anunderlying surface portion 7410 of protrusion 7406, at the undercut7408, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 7412 of protrusion 7406.

The outer articulation surface 7402 of implantable artificial femoral orhumeral head resurfacing element 7400 preferably comprises a hexagonalconfiguration pattern, which includes hexagonal articulating surfaceportions 7420 defined by peripheral channels 7424. Peripheral channels7424 are preferably interconnected and continuous and are provided toallow synovial fluid to pass through for lubrication of the articulationsurface 7402. Additionally, the hexagonal recessed configurationprovides for reduced surface contact area, which reduces friction. It isappreciated that, even though the illustrated embodiment shows ahexagonal configuration, any suitable configuration of channels andsurface portions may be provided.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial femoral head resurfacingelement 7400 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 64A and 64B, which are respectivepictorial and sectional illustrations of an implantable artificialfemoral or humeral head resurfacing element constructed and operative inaccordance with still another preferred embodiment of the presentinvention. The implantable artificial femoral or humeral headresurfacing element is intended for mounting onto a natural femoral orhumeral head in accordance with a preferred embodiment of the presentinvention.

As seen in FIGS. 64A and 64B, an implantable artificial femoral orhumeral head resurfacing element, designated by reference numeral 7500,is formed preferably by injection molding of polyurethane. Preferredpolyurethane materials are described hereinbelow.

Preferably, implantable artificial femoral or humeral head resurfacingelement 7500 is of generally uniform thickness, other than at its apexwhich is thickened, is symmetric about an axis 7501 and defines anhemispherical outer articulation surface 7502 and a generallyhemispherical inner bone engagement surface 7504, having a beveled edge7505, which preferably has formed thereon, at any suitable locationbetween its apex and its rim, a generally annular inwardly extendingprotrusion 7500, preferably defining a generally annular undercut 7508.Alternatively, the protrusion 7506 may be any other suitablenon-annular, open or closed, generally peripheral protrusion. Theprotrusion 7506 is preferably arranged for snap-fit engagement withcorresponding groove formed by reaming of a femoral or humeral head.

Preferably, the protrusion 7506 has a cross-sectional configuration, ascan be readily seen in FIG. 64B, which is characterized in that anunderlying surface portion 7510 of protrusion 7506, at the undercut7508, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 7512 of protrusion 7506.

The outer articulation surface 7502 of implantable artificial femoral orhumeral head resurfacing element 7500 preferably comprises a hexagonalconfiguration pattern, which includes hexagonal recessed surfaceportions 7520 defined by peripheral articulating surface elements 7524.Recessed surface portions 7520 may be connected or isolated from eachother and are provided to allow for the accumulation of synovial fluidfor lubrication of the articulation surface 7502. Additionally, thehexagonal recessed configuration provides for reduced surface contactarea, which reduces friction. It is appreciated that, even though theillustrated embodiment shows a hexagonal configuration, any suitableconfiguration of articulating surface elements and recessed surfaceportions may be provided.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial femoral head resurfacingelement 7500 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 65A, 65B and 65C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial femoral head resurfacing element constructed andoperative in accordance with a further preferred embodiment of thepresent invention. The implantable artificial femoral head resurfacingelement is intended for mounting onto a natural femoral head inaccordance with a preferred embodiment of the present invention.

As seen in FIGS. 65A, 65B and 65C, an implantable artificial femoralhead resurfacing element, designated by reference numeral 7550, isformed preferably be injection molding of polyurethane over areinforcing deformation control element. Preferred polyurethanematerials are described hereinbelow.

Preferably, implantable artificial femoral head resurfacing element 7550is of generally uniform thickness, other than at its apex which isthickened, is symmetric about an axis 7551 and defines an hemisphericalouter articulation surface 7552 and a generally hemispherical inner boneengagement surface 7554, having a beveled edge 7555, which preferablyhas formed thereon, at any suitable location between its apex and itsrim, a generally annular inwardly extending protrusion 7556, preferablydefining a generally annular undercut 7558. Alternatively, theprotrusion 7556 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The protrusion 7556 is preferablyarranged for snap-fit engagement with a corresponding groove formed byreaming of a femoral head.

Preferably, the protrusion 7556 has a cross-sectional configuration, ascan be readily seen in FIG. 65B, which is characterized in that anunderlying surface portion 7560 of protrusion 7556, at the undercut7558, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 7562 of protrusion 7556.

It is a particular feature of the artificial femoral head resurfacingelement 7550 that it includes an internal reinforcing deformationcontrol element, which is designated by reference numeral 7564 andillustrated pictorially in FIG. 65C. The deformation control element7564 is preferably formed of woven high performance fibers, such ascarbon fibers, KEVLAR®, DYNEEMA®, and glass fibers, and has an overallgenerally truncated spherical configuration defined by arched cut-outs7566 separated by flaps 7568 which terminate in thickened portions 7570.It is seen that insert 7564 is preferably molded entirely withinartificial femoral head resurfacing element 7550.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial femoral head resurfacingelement 7550 at the apex thereof, any suitable portion thereof may be ofnon-uniform thickness.

Reference is now made to FIGS. 66A, 66B, and 66C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a further preferred embodiment of the present inventionand which is particularly suitable for use in a hip joint.

As seen in FIGS. 66A, 66B, and 66C, an implantable artificial acetabularsocket, designated by reference numeral 7600, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 7600 defines aninner surface 7602 which is symmetric about an axis 7601. Acetabularsocket 7600 also preferably has a beveled edge 7603 and defines agenerally hemispherical outer bone engagement surface 7604 whichpreferably has formed thereon, at any suitable location between its apexand its rim, a generally annular outwardly extending protrusion 7606,preferably defining a generally annular undercut 7608. Alternatively,the protrusion 7606 may be any other suitable non-annular, open orclosed, generally peripheral, protrusion. The protrusion 7606 ispreferably arranged for snap-fit engagement with a corresponding grooveformed by reaming of a bone, examples of which are describedhereinabove.

Preferably, the protrusion 7606 has a cross-sectional configuration, ascan be readily seen in FIG. 66B, which is characterized in that anunderlying surface portion 7610 of protrusion 7606, at the undercut7608, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 7612 of protrusion 7606.

It is a particular feature of the implantable artificial acetabularsocket 7600 that a portion of outer bone engagement surface 7604 thereofdefines a thickened portion 7614, preferably extending from a locationgenerally atop inner apex 7616 of acetabular socket 7600 to theprotrusion 7606. Thickened portion 7614 is preferably aligned with thenatural acetabular recess, and is provided to allow a proper fit with areamed acetabulum, without requiring reaming of the entire surface ofthe acetabulum down to the level of the acetabular recess, as describedhereinbelow with reference to FIG. 69A. The thickened portion 7614preferably allows for a less invasive procedure and also provides athicker shock absorbing surface. It is appreciated that, even though theillustrated embodiment shows a circular configuration, any suitableconfiguration of thickened portion 7614 may be provided.

It is appreciated that thickened portion 7614 of acetabular socket 7600may alternatively be oriented, as described hereinbelow with referenceto FIG. 69B, so as to align thickened portion 7614 with the area ofgreatest applied force.

Reference is now made to FIGS. 67A, 67B, and 67C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a further preferred embodiment of the present inventionand which is particularly suitable for use in a hip

As seen in FIGS. 67A, 67B, and 67C, an implantable artificial acetabularsocket, designated by reference numeral 7700, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 7700 defines aninner surface 7702 which is symmetric about an axis 7701. Acetabularsocket 7700 also preferably has a beveled edge 7703 and defines agenerally hemispherical outer bone engagement surface 7704 whichpreferably has formed thereon, at any suitable location between its apexand its rim, a generally annular outwardly extending protrusion 7706,preferably defining a generally annular undercut 7708. Alternatively,the protrusion 7706 may be any other suitable non-annular, open orclosed, generally peripheral, protrusion. The protrusion 7706 ispreferably arranged for snap-fit engagement with a corresponding grooveformed by reaming of a bone, examples of which are describedhereinabove.

Preferably, the protrusion 7706 has a cross-sectional configuration, ascan be readily seen in FIG. 67B, which is characterized in that anunderlying surface portion 7710 of protrusion 7706, at the undercut7708, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 7712 of protrusion 7706.

It is a particular feature of the implantable artificial acetabularsocket 7700 that a portion of outer bone engagement surface 7704 thereofdefines multiple thickened portions 7714 and 7715, preferably extendingfrom a location generally atop inner apex 7716 of acetabular socket 7700to the protrusion 7706. Thickened portion 7714 is preferably alignedwith the natural acetabular recess, and is provided to allow a properlit with a reamed acetabulum, without requiring reaming of the entiresurface of the acetabulum down to the level of the acetabular recess, asdescribed hereinbelow with reference to FIG. 69C. The thickened portion7714 preferably allows for a less invasive procedure and also provides athicker shock absorbing surface. It is appreciated that, even though theillustrated embodiment shows a circular configuration, any suitableconfiguration of thickened portion 7714 may be provided. Thickenedportion 7715 of acetabular socket 7600 is oriented, as describedhereinbelow with reference to FIG. 69C, so as to be aligned with thearea of greatest applied force.

Reference is now made to FIGS. 68A, 68B, and 68C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a further preferred embodiment of the present inventionand which is particularly suitable for use in a hip

As seen in FIGS. 68A, 68B, and 68C, an implantable artificial acetabularsocket, designated by reference numeral 7900, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 7900 defines aninner surface 7902 which is symmetric about an axis 7901. Acetabularsocket 7900 also preferably has a beveled edge 7903 and defines agenerally hemispherical outer bone engagement surface 7904 whichpreferably has formed thereon, at any suitable location between its apexand its rim, a generally annular outwardly extending protrusion 7906,preferably defining a generally annular undercut 7908. Alternatively,the protrusion 7906 may be any other suitable non-annular, open orclosed, generally peripheral, protrusion. The protrusion 7906 ispreferably arranged for snap-fit engagement with a corresponding grooveformed by reaming of a bone, examples of which are describedhereinabove.

Preferably, the protrusion 7906 has a cross-sectional configuration, ascan be readily seen in FIG. 68B, which is characterized in that anunderlying surface portion 7910 protrusion 7906, at the undercut 7908,defines a slope which is sharper than a corresponding slope of anoverlying surface portion 7912 of protrusion 7906.

It is a particular feature of the implantable artificial acetabularsocket 7900 that a portion of outer bone engagement surface 7904 thereofdefines a thickened portion 7914, preferably extending from a locationgenerally atop inner apex 7916 of acetabular socket 7900 to theprotrusion 7906. Thickened portion 7914 is preferably aligned with thepeak direction of the joint reaction force of the joint with which it isarticulating. Thickened portion 7914 also preferably includes hollowportion 7918, which provides for attenuation of the stresses incurred atthe joint. It is appreciated that, even though the illustratedembodiment shows a generally circular configuration, any suitableconfiguration of thickened portion 7914 and hollow portion 7918 may beprovided.

Reference is now made to FIGS. 69A, 69B, 69C and 69D, which aresectional illustrations of a hip joint employing the implantableartificial acetabular sockets of FIGS. 66A-68C implanted in a reamedacetabulum.

As seen in FIG. 69A, implantable artificial acetabular socket 7600 ofFIGS. 66A-66C is shown implanted in acetabulum 7950 in a firstorientation, where thickened portion 7614 is aligned with the naturalacetabular recess 7952. Provision of thickened portion 7614 allowsacetabular socket 7600 to fit into acetabulum 7950 without requiringreaming of a hemispherical portion thereof, as indicated by dotted lines7954. This allows for a less invasive procedure and also provides athicker shock absorbing surface.

FIG. 69B illustrates implantable artificial acetabular socket 7600 ofFIGS. 66A-66C implanted in acetabulum 7960 in a second orientation,where thickened portion 7614 is oriented so as to align thickenedportion 7614 with the area of greatest applied force.

FIG. 69C illustrates implantable artificial acetabular socket 7700 ofFIGS. 67A-67C implanted in acetabulum 7970. Thickened portion 7714 isaligned with the natural acetabular recess 7972. Provision of thickenedportion 7714 allows acetabular socket 7700 to fit into acetabulum 7970without requiring reaming of a hemispherical portion thereof, asindicated by dotted lines 7974. This allows for a less invasiveprocedure and also provides a thicker shock absorbing surface. Thisembodiment requires additional reaming over that shown in FIG. 69A, toallow for the placement of thickened portion 7715 in the area ofgreatest applied force.

FIG. 69D shows implantable artificial acetabular socket 7900 of FIGS.68A-68C implanted in acetabulum 7980, where thickened portion 7914 isoriented so as to align thickened portion 7914 with the area of greatestapplied force. As seen in FIG. 69D, hollow portion 7918 is provided forattenuation of the stresses incurred at the joint.

Reference is now made to FIGS. 70A, 70B, and 70C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a further preferred embodiment of the present invention.

Preferably, implantable artificial acetabular socket 8000 is ofgenerally uniform thickness, is symmetric about an axis 8001 and definesan hemispherical concave inner articulation surface 8002, having abeveled edge 8003, and a generally hemispherical outer bone engagementsurface 8004, which preferably has formed thereon, at any suitablelocation between its apex and its rim, a generally annular outwardlyextending protrusion 8006, preferably defining a generally annularundercut 8008. Alternatively, the protrusion 8006 may be any othersuitable non-annular, open or closed, generally peripheral, protrusion.The protrusion 8006 is preferably arranged for snap-fit engagement witha corresponding groove formed by reaming of a bone, examples of whichare described hereinabove.

Preferably, the protrusion 8006 has a cross-sectional configuration, ascan be readily seen in FIG. 70B, which is characterized in that anunderlying surface portion 8010 of protrusion 8006, at the undercut8008, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 8012 of protrusion 8006.

It is a particular feature of the implantable artificial acetabularsocket 8000 that an edge portion 8020 thereof is formed with an inwardgroove 8022. Inward groove 8022 is provided to allow for the growth ofbone or fibrous tissue following the implantation of acetabular socket8000 and to promote biological fixation of acetabular socket 8000.

Reference is now made to FIGS. 71A, 71B, and 71C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a further preferred embodiment of the present invention.

Preferably, implantable artificial acetabular socket 8100 is ofgenerally uniform thickness, is symmetric about an axis 8101 and definesan hemispherical concave inner articulation surface 8102, having abeveled edge 8103, and a generally hemispherical outer bone engagementsurface 8104, which preferably has formed thereon, at any suitablelocation between its apex and its rim, a generally annular outwardlyextending protrusion 8106, preferably defining a generally annularundercut 8108. Alternatively, the protrusion 8106 may be any othersuitable non-annular, open or closed, generally peripheral, protrusion.The protrusion 8106 is preferably arranged for snap-fit engagement witha corresponding groove formed by reaming of a bone, examples of whichare described hereinabove.

Preferably, the protrusion 8106 has a cross-sectional configuration, ascan be readily seen in FIG. 71B, which is characterized in that anunderlying surface portion 8110 of protrusion 8106 at the undercut 8108,defines a slope which is sharper than a corresponding slope of anoverlying surface portion 8112 of protrusion 8106.

It is a particular feature of the implantable artificial acetabularsocket 8100 that a lower portion 8120 of outer bone engagement surface8104 is formed with an inward groove 8122. Inward groove 8122 isprovided to allow for the growth of bone or fibrous tissue following theimplantation of acetabular socket 8100 and to promote biologicalfixation of acetabular socket 8100.

Reference is now made to FIGS. 72A, 72B, and 72C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a further preferred embodiment of the present invention.

Preferably, implantable artificial acetabular socket 8200 is ofgenerally uniform thickness, is symmetric about an axis 8201 and definesan hemispherical concave inner articulation surface 8202, having abeveled edge 8203, and a generally hemispherical outer bone engagementsurface 8204, which preferably has formed thereon, at any suitablelocation between its apex and its rim, a generally annular outwardlyextending protrusion 8206, preferably defining a generally annularundercut 8208. Alternatively, the protrusion 8206 may be any othersuitable non-annular, open or closed, generally peripheral, protrusion.The protrusion 8206 is preferably arranged for snap-fit engagement witha corresponding groove formed by reaming of a bone, examples of whichare described hereinabove.

Preferably, the protrusion 8206 has a cross-sectional configuration, ascan be readily seen in FIG. 72B, which is characterized in that anunderlying surface portion 8210 of protrusion 8206, at the undercut8208, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 8212 of protrusion 8206.

It is a particular feature of the implantable artificial acetabularsocket 8200 that a lower portion 8220 of outer bone engagement surface8204 is formed with multiple inward grooves 8222. Multiple inwardgrooves 8222 are provided to allow for the growth of bone or fibroustissue following the implantation of acetabular socket 8200 and topromote biological fixation of acetabular socket 8200.

Reference is now made to FIGS. 73A and 73B, which are respectivepictorial and sectional illustrations of an implantable artificialfemoral or humeral head resurfacing element constructed and operative inaccordance with still another preferred embodiment of the presentinvention. The implantable artificial femoral or humeral headresurfacing element is intended for mounting onto a natural femoral orhumeral head in accordance with a preferred embodiment of the presentinvention.

As seen in FIGS. 73A and 73B, an implantable artificial femoral orhumeral head resurfacing element, designated by reference numeral 8300,is formed preferably by injection molding of polyurethane. Preferredpolyurethane materials are described hereinbelow.

Preferably, implantable artificial femoral or humeral head resurfacingelement 8300 is of generally uniform thickness other than at its apexwhich is thickened, is symmetric about an axis 8301 and defines anhemispherical outer articulation surface 8302 and a generallyhemispherical inner bone engagement surface 8304, having a beveled edge8305, which preferably has formed thereon, at any suitable locationbetween its apex and its rim, a generally annular inwardly extendingprotrusion 8306, preferably defining a generally annular undercut 8308.Alternatively, the protrusion 8306 may be any other suitablenon-annular, open or closed, generally peripheral, protrusion. Theprotrusion 8306 is preferably arranged for snap-fit engagement with acorresponding groove formed by reaming of a femoral or humeral head.

Preferably, the protrusion 8306 has a cross-sectional configuration, ascan be readily seen in FIG. 73B, which is characterized in that anunderlying surface portion 8310 of protrusion 8306, at the undercut8308, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 8312 of protrusion 8306.

The outer articulation surface 8302 of implantable artificial femoral orhumeral head resurfacing element 8300 preferably includes a peripheralrecess 8314, generally located proximate to the edge of outerarticulation surface 8302. Preferably, radio opaque ring element 8316 isembedded in peripheral recess 8314. Provision of radio opaque ringelement 8316 provides the ability to monitor the position of artificialfemoral or humeral head resurfacing element 8300 after it has beenimplanted. Radio opaque ring element 8316 is preferably comprised ofmetal, barium sulfate, zirconium oxide or any other suitable radioopaque material, and may be molded and inserted into artificial femoralor humeral head resurfacing element 8300 or integrally formed therewith.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial femoral or humeral headresurfacing element 8300 at the apex thereof, any suitable portionthereof may be of non-uniform thickness.

It is appreciated that, even though the illustrated embodiment shows theprovision of a radio opaque ring element in a femoral or humeral head,the provision of a radio opaque ring, element is not limited to afemoral or humeral head, but may be included with any of the artificialimplants described in this application.

Reference is now made to FIGS. 74A and 74B, which are respectivepictorial and sectional illustrations of an implantable artificialfemoral or humeral head resurfacing element constructed and operative inaccordance with still another preferred embodiment of the presentinvention. The implantable artificial femoral or humeral headresurfacing element is intended for mounting onto a natural femoral orhumeral head in accordance with a preferred embodiment of the presentinvention.

As seen in FIGS. 74A and 74B, an implantable artificial femoral orhumeral head resurfacing element, designated by reference numeral 8400,is formed preferably by injection molding of polyurethane. Preferredpolyurethane materials are described hereinbelow.

Preferably, implantable artificial femoral or humeral head resurfacingelement 8400 is of generally uniform thickness, other than at its apexwhich is thickened, is symmetric about an axis 8401 and defines anhemispherical outer articulation surface 8402 and a generallyhemispherical inner bone engagement surface 8404, having a beveled edge8405, which preferably has formed thereon, at any suitable locationbetween its apex and its rim, a generally annular inwardly extendingprotrusion 8406, preferably defining a generally annular undercut 8408.Alternatively, the protrusion 8406 may be any other suitablenon-annular, open or closed, generally peripheral, protrusion. Theprotrusion 8406 is preferably arranged for snap-fit engagement with acorresponding groove formed by reaming of a femoral or humeral head.

Preferably, the protrusion 8406 has a cross-sectional configuration, ascan be readily seen in FIG. 74B, which is characterized in that anunderlying surface portion 8410 of protrusion 8406, at the undercut8408, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 8412 of protrusion 8406.

The inner bone engagement surface 8404 of implantable artificial femoralor humeral head resurfacing element 8400 preferably includes aperipheral recess 8414, generally located proximate to the edge of innerbone engagement surface 8404. Preferably, radio opaque ring element 8416is embedded in peripheral recess 8414. Provision of radio opaque ring,element 8416 provides the ability to monitor the position of artificialfemoral or humeral head resurfacing element 8400 after it has beenimplanted. Radio opaque ring element 8416 is preferably comprised ofmetal, barium sulfate, zirconium oxide or any other suitable radioopaque material, and may be molded and inserted into artificial femoralor humeral head resurfacing element 8400 or integrally formed therewith.

It is appreciated that, even though the illustrated embodiment shows thenon-uniform thickness portion of artificial femoral or humeral headresurfacing element 8400 at the apex thereof any suitable portionthereof may be of non-uniform thickness.

Reference is now made to FIGS. 75A and 75B, which are respectivepictorial and sectional illustrations of an implantable artificialfemoral or humeral head resurfacing element constructed and operative inaccordance with still another preferred embodiment of the presentinvention. The implantable artificial femoral or humeral headresurfacing element is intended for mounting onto a natural femoral orhumeral head in accordance with a preferred embodiment of the presentinvention.

As seen in FIGS. 75A and 75B, an implantable artificial femoral orhumeral head resurfacing element, designated by reference numeral 8500,is formed preferably by injection molding of polyurethane. Preferredpolyurethane materials are described hereinbelow.

Preferably, implantable artificial femoral or humeral head resurfacingelement 8500 is of generally uniform thickness, other than at its apexwhich is thickened, is symmetric about an axis 8501 and defines anhemispherical outer articulation surface 8502 and a generallyhemispherical inner bone engagement surface 8504, having a beveled edge8505, which preferably has formed thereon, at any suitable locationbetween its apex and its rim, a generally annular inwardly extendingprotrusion 8506, preferably defining a generally annular undercut 8508.Alternatively, the protrusion 8506 may be any other suitablenon-annular, open or closed, generally peripheral, protrusion. Theprotrusion 8506 is preferably arranged for snap-fit engagement with acorresponding groove formed by reaming of a femoral or humeral head.

Preferably, the protrusion 8506 has a cross-sectional configuration, ascan be readily seen in FIG. 75B, which is characterized in that anunderlying surface portion 8510 of protrusion 8506, at the undercut8508, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 8512 of protrusion 8506.

An edge surface 8513 of implantable artificial femoral or humeral headresurfacing element 8500 preferably includes a peripheral recess 8514.Preferably, radio opaque ring element 8516 is embedded in peripheralrecess 8514. Provision of radio opaque ring element 8516 provides theability to monitor the position of artificial femoral or humeral headresurfacing element 8500 after it has been implanted. Radio opaque ringelement 8516 is preferably comprised of metal, barium sulfate, zirconiumoxide or any other suitable radio opaque material, and may be molded andinserted into artificial femoral or humeral head resurfacing element8500 or integrally formed therewith.

Reference is now made to FIGS. 76A and 76B, which are respectivepictorial and sectional illustrations of an implantable artificialacetabular socket constructed and operative in accordance with apreferred embodiment of the present invention and which is particularlysuitable for use in a hip joint.

As seen in FIGS. 76A and 76B, an implantable artificial acetabularsocket, designated by reference numeral 8600, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 8600 is ofgenerally uniform thickness, is symmetric about an axis 8601 and definesan hemispherical concave inner articulation surface 8602 and a generallyhemispherical outer bone engagement surface 8604, which preferably hasformed thereon, at any suitable location between its apex and its rim, agenerally annular outwardly extending protrusion 8606, preferablydefining a generally annular undercut 8608. Alternatively, theprotrusion 8606 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The protrusion 8606 is preferablyarranged for snap-fit engagement with a corresponding groove formed byreaming of a bone, examples of which are described hereinabove.

Preferably, the protrusion 8606 has a cross-sectional configuration, ascan be readily seen in FIG. 76B, which is characterized in that anunderlying surface portion 8610 of protrusion 8606, at the undercut8608, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 8612 of protrusion 8606.

It is a particular feature of the implantable artificial acetabularsocket 8600 that a portion of outer bone engagement surface 8604 thereofdefines a thickened portion 8614, preferably extending from a locationgenerally adjacent protrusion 8606. Thickened portion 8614 is preferablymolded to correspond with the shape of the acetabular notch. Thickenedportion 8614 is provided to add stability to acetabular socket 8600 onceimplanted, by minimizing rotational movement and preventing rotationaldislodgment.

Reference is now made to FIGS. 77A and 77B, which are respectivepictorial and sectional illustrations of an implantable artificialacetabular socket constructed and operative in accordance with apreferred embodiment of the present invention and which is particularlysuitable for use in a hip joint.

As seen in FIGS. 77A and 77B, an implantable artificial acetabularsocket, designated by reference numeral 8700, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 8700 is ofgenerally uniform thickness, is symmetric about an axis 8701 and definesan hemispherical concave inner articulation surface 8702 and a generallyhemispherical outer bone engagement surface 8704, which preferably hasformed thereon, at any suitable location between its apex and its rim, agenerally annular outwardly extending protrusion 8706, preferablydefining a generally annular undercut 8708. Alternatively, theprotrusion 8706 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The protrusion 8706 is preferablyarranged for snap-fit engagement with a corresponding groove formed byreaming of a bone, examples of which are described hereinabove.

Preferably, the protrusion 8706 has a cross-sectional configuration, ascan be readily seen in FIG. 77B, which is characterized in that anunderlying surface portion 8710 or protrusion 8706, at the undercut8708, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 8712 of protrusion 8706.

As seen in FIGS. 77A and 77B, implantable artificial acetabular socket8700 is a less than full hemispherical, low profile acetabular socket,as can be readily seen from radius 8714, which shows a radius of thefull hemispherical socket that acetabular socket 8700 is similar to.Acetabular socket 8700 thus provides for implantation with less reamingof bone required.

Reference is now made to FIGS. 78A and 78B, which are respectivepictorial and sectional illustrations of an implantable artificialacetabular socket constructed and operative in accordance with apreferred embodiment of the present invention and which is particularlysuitable for use in a hip joint.

As seen in FIGS. 78A and 78B, an implantable artificial acetabularsocket, designated by reference numeral 8800, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 8800 is ofgenerally uniform thickness, is symmetric about an axis 8801 and definesan hemispherical concave inner articulation surface 8802 and a generallyhemispherical outer bone engagement surface 8804, which preferably hasformed thereon, at any suitable location between its apex and its rim, agenerally annular outwardly extending protrusion 8806, preferablydefining a generally annular undercut 8808. Alternatively, theprotrusion 8806 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The protrusion 8806 is preferablyarranged for snap-fit engagement with a corresponding groove formed byreaming of a bone, examples of which are described hereinabove.

Preferably, the protrusion 8806 has a cross-sectional configuration, ascan be readily seen in FIG. 78B, which is characterized in that anunderlying surface portion 8810 of protrusion 8806, at the undercut8808, defines a slope which is sharper than a corresponding, slope of anoverlying surface portion 8812 of protrusion 8806.

Implantable artificial acetabular socket 8800 also includes an extendedportion 8820, preferably provided to prevent dislocation of the femoralhead following insertion.

Reference is now made to FIGS. 79A and 79B, which are respectivepictorial and sectional illustrations of an implantable artificialacetabular socket constructed and operative in accordance with apreferred embodiment of the present invention and which is particularlysuitable for use in a hip joint.

As seen in FIGS. 79A and 79B, an implantable artificial acetabularsocket, designated by reference numeral 8900, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 8900 is ofgenerally uniform thickness, is symmetric about an axis 8901 and definesan hemispherical concave inner articulation surface 8902 and a generallyhemispherical outer bone engagement surface 8904, which preferably hasformed thereon, at any suitable location between its apex and its rim, agenerally annular outwardly extending protrusion 8906, preferablydefining a generally annular undercut 8908. Alternatively, theprotrusion 8906 may be any other suitable non-annular, open or closed,generally peripheral, protrusion. The protrusion 8906 is preferablyarranged for snap-fit engagement with a corresponding groove formed byreaming of a bone, examples of which are described hereinabove.

Preferably, the protrusion 8906 has a cross-sectional configuration, ascan be readily seen in FIG. 79B, which is characterized in that anunderlying surface portion 8910 of protrusion 8906, at the undercut8908, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 8912 of protrusion 8906.

It is a particular feature of the implantable artificial acetabularsocket 8900 that protrusion 8906 is arranged such that it is notorthogonal to axis 8901 and thus allows proper orientation of theartificial acetabular socket in an improperly reamed natural acetabulum.Implantable artificial acetabular socket 8900 is provided withprotrusion 8906 for engagement with a reamed acetabulum, where thereaming was performed in a less than desirable orientation.

Reference is now made to FIGS. 80A, 80B, and 80C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a preferred embodiment of the present invention andwhich is particularly suitable for use in a hip joint.

As seen in FIGS. 80A, 80B and 80C, an implantable artificial acetabularsocket, designated by reference numeral 9000, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 9000 is ofgenerally uniform thickness, is symmetric about an axis 9001 and definesan hemispherical concave inner articulation surface 9002, having abeveled edge 9003, and a generally hemispherical outer bone engagementsurface 9004, which preferably has formed thereon, at any suitablelocation between its apex and its rim, a generally annular outwardlyextending, protrusion 9006, preferably defining a generally annularundercut 9008. Alternatively, the protrusion 9006 may be any othersuitable non-annular, open or closed, generally peripheral, protrusion.The protrusion 9006 is preferably arranged for snap-fit engagement witha corresponding groove formed by reaming of a bone, examples of whichare described hereinabove.

Preferably, the protrusion 9006 has a cross-sectional configuration, ascan be readily seen in FIG. 80B, which is characterized in that anunderlying surface portion 9010 of protrusion 9006, at the undercut9008, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 9012 of protrusion 9006.

It is a particular feature of the implantable artificial acetabularsocket 9000 that a portion of outer bone engagement surface 9004,preferably the portion located between protrusion 9006 and the apexthereof, includes a plurality of hollow annular protrusions 9020integral with surface 9004 but protruding beyond surface 9004. Annularprotrusions 9020 are shaped with an undercut and are in contact withprepared acetabulum leaving a gap between the prepared acetabularsurface and implant surface 9004. Annular protrusions 9020 providelocalized areas of low contact area and thus high localized stress. Withtime, the high localized stress allows controlled subsidence of theimplant until surface 9004 comes into contact with the acetabular bonesurface. The controlled subsidence of the implant also enables the bonysurface to completely surround the undercut shape of annular protrusions9020, thus further improving the fixation of the implant.

Reference is now made to FIGS. 81A, 81B, and 81C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a preferred embodiment of the present invention andwhich is particularly suitable for use in a hip joint.

As seen in FIGS. 81A, 81B and 81C, an implantable artificial acetabularsocket, designated by reference numeral 9100, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 9100 is ofgenerally uniform thickness, is symmetric about an axis 9101 and definesan hemispherical concave inner articulation surface 9102, having abeveled edge 9103, and a generally hemispherical outer bone engagementsurface 9104, which preferably has formed thereon, at any suitablelocation between its apex and its rim, a generally annular outwardlyextending protrusion 9106, preferably defining a generally annularundercut 9108. Alternatively, the protrusion 9106 may be any othersuitable non-annular, open or closed, generally peripheral, protrusion.The protrusion 9106 is preferably arranged for snap-fit engagement witha corresponding groove formed by reaming of a bone, examples of whichare described hereinabove.

Preferably, the protrusion 9106 has a cross-sectional configuration, ascan be readily seen in FIG. 81B, which is characterized in that anunderlying surface portion 9110 of protrusion 9106, at the undercut9108, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 9112 of protrusion 9106.

It is a particular feature of the implantable artificial acetabularsocket 9100 that a portion of outer bone engagement surface 9104,preferably the portion located between protrusion 9106 and the apexthereof, includes a plurality of annular recesses 9120 enclosing annularprotrusions 9122. Annular protrusions 9122 are desired with an undercutand are in contact with prepared acetabulum leaving a gap between theprepared acetabular surface and implant surface 9104. Annularprotrusions 9112 provide localized areas of low contact area and thushigh localized stress. With time, the high localized stress allowscontrolled subsidence of the implant until implant surface 9104 comesinto contact with the acetabular bone surface. The controlled subsidenceof the implant also enables bone or fibrous tissue to completely fill inthe annular recesses 9120 and undercut of annular protrusion 9122 tofurther stabilize the implant in place through biological fixation.

Reference is now made to FIGS. 82A, 82B, and 82C, which are respectivepictorial, sectional and partially cut away illustrations of animplantable artificial acetabular socket constructed and operative inaccordance with a preferred embodiment of the present invention andwhich is particularly suitable for use in a hip joint.

As seen in FIGS. 82A, 82B and 82C, an implantable artificial acetabularsocket, designated by reference numeral 9200, is formed preferably byinjection molding of polyurethane. Preferred polyurethane materials aredescribed hereinbelow.

Preferably, implantable artificial acetabular socket 9200 is ofgenerally uniform thickness, is symmetric about an axis 9201 and definesan hemispherical concave inner articulation surface 9202, having abeveled edge 9203, and a generally hemispherical outer bone engagementsurface 9204, which preferably has formed thereon, at any suitablelocation between its apex and its rim, a generally annular outwardlyextending protrusion 9206, preferably defining a generally annularundercut 9208. Alternatively, the protrusion 9206 may be any othersuitable non-annular, open or closed, generally peripheral, protrusion.The protrusion 9206 is preferably arranged for snap-fit engagement witha corresponding groove formed by reaming of a bone, examples of whichare described hereinabove.

Preferably, the protrusion 9206 has a cross-sectional configuration, ascan be readily seen in FIG. 82B, which is characterized in that anunderlying surface portion 9210 of protrusion 9206, at the undercut9208, defines a slope which is sharper than a corresponding slope of anoverlying surface portion 9212 of protrusion 9206.

It is a particular feature of the implantable artificial acetabularsocket 9200 that a portion of outer bone engagement surface 9204,preferably the portion located between protrusion 9206 and the apexthereof, includes a plurality of annular protrusions 9220. Annularprotrusions 9220 are preferably arranged for engagement withcorresponding recesses formed by reaming of a bone, to provide enhancedbiological fixation of acetabular socket 9200 following insertionthereof.

Reference is now made to FIG. 83, which is a pictorial illustration ofan implantable artificial acetabular socket 9300, constructed andoperative in accordance with another preferred embodiment of the presentinvention, which is particularly suitable for use in a hip joint.Implantable artificial acetabular socket 9300 is constructed with atextured thin element 9302, preferably made of titanium, with an annularconfiguration, molded onto an outer surface 9304 of acetabular socket9300. The provision of element 9302 provides enhanced biologicalfixation of acetabular socket 9300 following insertion thereof. It isappreciated that element 9302 may cover the entire surface 9304 or anysuitable portion thereof.

Reference is now made to FIG. 84, which is a pictorial illustration ofan implantable artificial acetabular socket 9400, constructed andoperative in accordance with another preferred embodiment of the presentinvention, which is particularly suitable for use in a hip joint.Implantable artificial acetabular socket 9400 is constructed with anarray 9402 of textured thin elements 9404, preferably made of titanium,with segmented configuration, molded onto outer surface 9406 ofacetabular socket 9400. The provision of elements 9404 provides enhancedbiological fixation of acetabular socket 9400 following insertionthereof It is appreciated that, even though the illustrated embodimentshows elements 9404 having a square configuration arrangedsymmetrically, elements 9404 may have any suitable shape andarrangement.

Reference is now made to FIGS. 85A and 85B, which are sectionalillustrations of the installation of an artificial femoral resurfacinghead on a reamed femoral head, in accordance with a preferred embodimentof the present invention. As seen in FIG. 85A, femoral head 9500 hasbeen reamed to define a seating location 9502, preparatory to theplacement of a press fit femoral head resurfacing element 9504. FIG. 85Bshows element 9504 following placement thereof on reamed femoral head9500.

Reference is now made to FIGS. 86A and 86B, which are sectionalillustrations of the installation of an artificial femoral resurfacinghead on a reamed femoral head, in accordance with a preferred embodimentof the present invention. As seen in FIG. 86A, femoral head 9510 hasbeen reamed to define a seating location 9512, preparatory to theplacement of a snap fit femoral head resurfacing element 9514. FIG. 86Bshows element 9514 following placement thereof on reamed femoral head 9510.

Reference is now made to FIGS. 87A, 87B, 87C and 87D, which aresectional illustrations of various stages of installation of amulti-part artificial femoral resurfacing head on a reamed femoral headin accordance with still another preferred embodiment of the presentinvention. As seen in FIG. 87A, femoral head 9520 has been reamed todefine a seating location 9522, preparatory to the placement of a snapfit femoral head interface element 9524. FIG. 87B shows element 9524,preferably made of polyurethane, following placement thereof on reamedfemoral head 9520. FIG. 87C shows the femoral head of FIG. 87B,preparatory to the placement of a press fit femoral head resurfacingelement 9526. Press fit femoral head resurfacing element 9526 is made ofany suitable bearing surface materials, such as polyurethane, metal orceramic. FIG. 87D shows element 9526 following placement thereof onfemoral head interface element 9524.

Reference is now made to FIGS. 88A, 88B, 88C and 88D, which aresectional illustrations of various stages of installation of amulti-part artificial femoral resurfacing head on a reamed femoral headin accordance with still another preferred embodiment of the presentinvention. As seen in FIG. 88A, femoral head 9530 has been reamed todefine a seating location 9532, preparatory to the placement of a snapfit femoral head interface element 9534. FIG. 88B shows element 9534,preferably made of polyurethane, following placement thereof on reamedfemoral head 9530. FIG. 88C shows the femoral head of FIG. 88B,preparatory to the placement of a press fit femoral head resurfacingelement 9536. Press fit femoral head resurfacing element 9536 is made ofany suitable bearing surface materials, such as polyurethane, metal orceramic. FIG. 88D shows element 9536 following placement thereof onfemoral head interface element 9534.

Reference is now made to FIGS. 89A and 89B, which are sectionalillustrations of various stages of installation of a multi-partartificial femoral resurfacing head on a reamed femoral head inaccordance with still another preferred embodiment of the presentinvention. As seen in FIG. 89A, femoral head 9540 has been reamed todefine a seating location 9542, preparatory to the placement of a pressfit femoral head interface element 9544. Press fit femoral headinterface element 9544 may be made of polyurethane, metal or any othersuitable material. FIG. 89B shows element 9544, following placementthereof on reamed femoral head 9540 and the placement of a press fitfemoral head resurfacing element 9546 thereon. Press fit femoral headresurfacing element 9546 is preferably made of any suitable bearingsurface materials such as polyurethane, metal or ceramic.

It is appreciated that the embodiments shown in FIGS. 85A-89B allow fora variety of combinations of snap fit and press fit femoral headinterface elements and resurfacing elements. These elements may becomprised of different substances, to provide suitable rigidity andflexibility of the articulation surface, as well as suitableconfigurations for implantation. Generally, the snap fit devices providefor more flexibility, and are formed preferably by injection molding ofpolyurethane, while the press fit devices generally provide morerigidity, and may be formed by injection molding of polyurethane, or maybe formed from any other suitable material, such as metal or ceramic, byany suitable method. Additionally, resurfacing elements 9526, 9536 and9546, described in reference to FIGS. 87A-89B, may be molded or sprayeddirectly onto interface elements 9524, 9534 or 9544, respectively, ormay be formed by dipping onto interface elements 9524, 9534 or 9544,prior to their implantation on machined femoral head 9520, 9530 or 9540,respectively.

Reference is now made to FIG. 90A, which is a sectional illustration ofa femoral head in accordance with another preferred embodiment of thepresent invention. As seen in FIG. 90A femoral head 9600 has been fittedwith a conventional femoral stem 9602. An artificial femoral headelement 9604 is mounted onto stem 9602. Artificial femoral head element9604 includes an articulation element 9606, preferably formed ofpolyurethane, overlying a rigid metal core element 9608, which alsoincludes a tapered trunnion for mounting core element 9608 ontoconventional stem 9602. Core element 9608 may be constructed of metal,ceramic or any other rigid material, and is preferably less flexiblethan articulation element 9606. Articulation element 9606 may be mountedor formed onto core element 9608 by spraying, dipping, injection or blowmolding or formed separately by any suitable means and assembledthereafter onto core element 9608.

Reference is now made to FIG. 90B, which is a sectional illustration ofa humeral head in accordance with another preferred embodiment of thepresent invention. As seen in FIG. 90B, humeral head 9650 has beenfitted with a conventional humeral stem 9652. An artificial humeral headelement 9654 is mounted onto stem 9652. Artificial humeral head element9654 includes an articulation element 9656, preferably formed ofpolyurethane, overlying a rigid metal core element 9658, which alsoincludes a tapered trunnion for mounting core element 9658 ontoconventional stem 9652. Core element 9658 may be constructed of metal,ceramic or any other rigid material, and is preferably less flexiblethan articulation element 9656. Articulation element 9656 may be mountedor formed onto core element 9658 by spraying, dipping, injection or blowmolding or formed separately by any suitable means and assembledthereafter onto core element 9658.

It is further appreciated that femoral and humeral heads of FIGS.90A-90B could be resurfacing, implants positioned directly to a suitablyprepared natural femoral or humeral head without a conventional stem.

Reference is now made to FIGS. 91A, 91B and 91C, which are sectionalillustrations showing bone growth adjacent to an implanted acetabularsocket in accordance with another preferred embodiment of the presentinvention. As seen in FIG. 91A, an acetabular socket 9700, similar toacetabular socket 9100 of FIGS. 81A-81C, is implanted in reamedacetabulum 9702. Acetabular socket 9700 includes recesses 9704. As seenin FIG. 91A, over time the acetabulum has remodeled itself to fillrecesses 9704. As seen in FIGS. 91B and 91C, different shaped recessesmay be provided along acetabular socket 9700. It is appreciated that theconfiguration pattern of recesses 9704 of the bone engagement surface9706 provides enhanced adhesion of acetabulum 9702 to socket 9700 andthus improves the stability of socket 9700. This configuration patterncould apply to any of the implant devices disclosed herein.

Reference is now made to FIG. 92, which is a simplified sectionalillustration of a bone engagement surface, textured in accordance withanother preferred embodiment of the present invention. The boneengagement surface of FIG. 92 provides enhanced bone adhesion andimproved stability.

As seen in FIG. 92, a portion of an artificial implantation device 9800,such as acetabular sockets described hereinabove, but not limited toacetabular sockets, having a bone engagement surface 9802, engages bone9804. Bone engagement surface 9801 includes a rough texture 9806superimposed on to at least a portion thereof It is appreciated thatbone engagement surface 9802 may be uniform, such as surface 1104 insocket 1100 shown in FIGS. 1A-1C, or may include various protrusions orrecesses, such as surface 9104 in socket 9100 of FIGS. 81A-81C. Overtime, bone cells, fibroblasts and tissue matrix 9808 fill the crevicesof rough texture 9806 along surface 9802, as shown in FIG. 92.

Reference is now made to FIGS. 93A and 93B, which are simplifiedpictorial illustrations of a method of modifying the texture of a boneengagement surface of an artificial implantation device, in accordancewith another preferred embodiment of the present invention.

FIG. 93A illustrates a method for modifying the surface of theartificial implantation device 9900, by mechanically providing surfaceroughness, such as by grit blasting. Grit blasting may be conductedwithout any preparatory steps, other than cleaning the contact surface9902 of implantation device 9900. Grit blasting can be accomplished withany suitable media capable of creating a texturized surface. If a nonmedical grade media is used then residual is preferably cleaned from theimplant surface to prevent initiation of a foreign body reaction.Alternatively, grit blasting may utilize Hydroxylapatite or any otherbioactive materials as the (grit media 9904. Artificial implantationdevice 9900 is rotated around its axis, as indicated by arrow 9906, andthe blast nozzle 9908 will be generally positioned at a right angle tothe rotating part.

Grit blasting may be hot grit blasting, utilizing heated gas. A heatingcycle, which is meant to soften the outer layers of the artificialimplantation device 9900, will precede the blasting phase in order tohelp embed the bioactive particles of grit media 9904 into the surface9902 of artificial implantation device 9900. Since the bioactiveparticles of grit media 9904 are harder than the heated surface 9902,particles will become embedded into surface 9902. This process will forma roughened texture that will act as the anchor for bone attachment. Inaddition, the resorption of the Hydroxylapatite with time will causebone growth into the voids that are created by the resorption of thegrit media. FIG. 93B shows the grit media 9902 implanted into contactsurface 9902 of artificial implantation device 9900.

Reference is now made to FIG. 94, which is a simplified pictorialillustration of another method of modifying the texture of the boneengagement surface or an artificial implantation device, in accordancewith yet another preferred embodiment of the present invention.

As seen in FIG. 94, contact surface 9950 of artificial implantationdevice 9952 is treated to provide surface roughness and surface porosityby forming at least one additional layer 9954 of sprayed material 9956.The spraying apparatus, described hereinbelow with reference to FIG. 95,may use feedstock configured as a rod or provided as powder. Thefeedstock rod or powder may be a neat elastomer, preferably of in equalor similar type of elastomer to the material from which artificialimplantation device is formed therefrom, such as polyurethane. Thefeedstock rod may be extruded from a premix of an elastomer andBioactive materials.

The surface roughness and surface porosity is provided preferably byco-spraying of an elastomer and bioactive materials composite coating.The premixed feedstock may be PU/HA (polyurethane/Hydroxylapatite), thusproviding a co-spraying of PU/HA A composite coating. The bioactivematerials are preferably hydroxylapatite or any other suitable calciumphosphate-containing materials. These bioactive materials cause thecontact surface 9950 of artificial implantation device 9952 to becomebioactive, stimulating bone growth to provide an adhesion of the implantto the bone and accelerate osteointegration.

The feedstock for this coating can be in powder form, where acombination of PU and HA powders are preferably blended in suitableratios and sprayed to form the desired coating. Alternatively, thefeedstock can be a PU rod that is co-sprayed with HA powder particlesthat are fed separately into the molten particle flow. The PU rod canalso be extruded with HA powder mixed within it so that a composite rodfeedstock is obtained. Alternatively, any other suitable method ofcombining the PU and the bioactive materials may be used. The rod willthen be fed directly through the spray device and the resulting coatingwill contain both HA and PU particles forming the desired matrix.

Reference is now made to FIG. 95, which is a simplified pictorialillustration of a spraying apparatus which may be used in the embodimentof FIG. 94.

As seen in FIG. 95, spraying apparatus 9960 is used, as describedhereinabove with reference to FIG. 94, to modify the contact surface9950 of artificial implantation device 9952 by coating contact surface9950. This coating is preferably provided using a combustion process,which utilizes an oxygen-fuel mixture and heats the particles as theyare fed through a gravity hopper through the center of the sprayingapparatus 9960. A nozzle 9964 directs the combustion gasses and themolten particles towards the contact surface 9950 of artificialimplantation device 9952. The combustion of the gasses occurs within achamber in the nozzle and a carrier gas is used to propel the moltenparticles forward, in the direction of arrows 9970, and prevent themfrom sticking to the nozzle walls. When using rod feedstock (in place ofpowder), atomizing gas is used to break the tip of the molten rod intodiscrete particles.

A coating of molten polyurethane particles can be applied to contactsurface 9950 of artificial implantation device 9952 in order to create arough porous surface into which the bone can grow. The process may startwith a preheating step that is designed to melt the surface of theimplant and provide for a chemical bond between the surface and thepolyurethane particles, although the process can be applied to a coldsurface as well. The thickness of the coating can be regulated.

The coating deposited using the above mentioned combustion spray processmay be a Polymer-Hydroxylapatite composite coating. This coating systemconsists of a combination of polyurethane particles that will beco-sprayed with HA powder. The resulting coating will form a polymerscaffold like structure that will entrap the HA particles within. Thiscomposite structure will help anchor the implant by enabling boneattachment to the exposed HA particles and eventually boneinterdigitation in the pores created as the HA resorbs with time.

Alternatively, a coating can be deposited onto the contact surface 9950of artificial implantation device 9952 by means of dipping, whereby aslurry is made of a polymer material, having a certain quantity ofbioactive particles mixed within it. The artificial implantation device9952 is dipped into the slurry, after which it is allowed to dry. As theslurry dries, a composite polymer/bioactive material coating is created,where the bioactive particles are trapped within the polymer matrix.

The coating may be an elastomer on elastomer coating, such as apolyurethane on polyurethane coating. The polyurethane coating can havea hardness of 55D and upward for enhancing bio-stability on the outersurface, while the artificial implantation device 9952 and contactsurface 9950 is of hardness 80A.

In addition to the enhanced bone adhesion methods described in referenceto FIGS. 91A-95, the contact surface of an artificial implantationdevice may also be treated using one of the following SurfaceModification processes: Atomic cleaning, adhesion promotion, moleculargrafting, cell attachment enhancement, and Plasma Enhanced ChemicalVapor Deposition (PECVD) coatings, such as implemented by the MetroLineSurface, Inc. Surface modification processes improve the articulatingproperties of the contact surface by reducing friction and therebyenhance the resistance to wear.

It is known in the art that in the vicinity of rigid implants, such asmetal implants, there are regions of stress shielding in some parts ofthe bone, meaning that such rigid implants take load formerlytransferred to the bone, thereby shielding the bone from the load andcausing bone resorption. This process has been observed in regions suchas in the proximal medial calcar after hip replacement, and such asunder the tibial component of knee replacements.

The implants of the present invention comprise flexible elements, andalso preferably include deformation control elements, resulting inimproved load distribution, which prevents or significantly reducesstress shielding.

As discussed hereinabove, it is appreciated that the stresses producedin the natural bone, such as in the natural acetabular socket, producecorresponding strains therein. Both the stresses and the strains havepositive medical implications which are expressed in bone remodeling.

It is further appreciated that the implants of the present invention areconstructed to control the stress distribution at the bone-implantinterface, and within the surrounding bone, resulting in a positive boneremodeling, creating a mechanical environment with conditions thatinitiate net remodeling activity growing new bone cells of structuralcharacteristics. This process prevents loosening of the devicesaccording to this invention and enhances the anchoring.

The following is a brief description of a best mode manufacturingprocess of the implantable artificial socket 1100 shown in FIGS. 1A to1C. The manufacturing process typically comprises the steps as describedhereinbelow. It is appreciated that the steps of the manufacturingprocess are monitored and controlled in order to assure the quality ofthe products meets the required standards.

Step 1. Material identification:

-   -   A preferable material used for manufacturing a cup used for        preparing the implantable artificial socket 1100 is        Polycarbonate Urethane Bionate 80A, which is supplied by Polymer        Technology Group Inc., 2810 7^(th) Street, Berkeley, Calif.        94710, U.S.A.

Step 2. Equipment used for Cup Manufacturing:

Step 2.1 Equipment use for pre-Injection drying:

-   -   A desiccant that has the ability to be connected directly to the        screw of an injection molding machine and reach 50 deg dew        point, is preferably used.

Step 2.2. Equipment use for Cup Injection:

-   -   The injection molding machine includes computerized data        acquisition ability and an 18-20 mm diameter cylinder, for        example an ARBURG 4020 device.

Step 2.3, Equipment use for Post-injection Curing:

-   -   Industrial oven capable of maintaining 80° C.±2° C. for        approximately 15 hours.

Step 3. Preprocess for the raw material:

-   -   The drying of the raw material is performed using a desiccant        dehumidifier, outside of a clean room.

Step 3.1. The Drying process typically includes the steps:

-   -   I. 12 hours at 65° C. [−50 dew point]    -   II. 4 hours at 93° C. [−50 dew point]    -   The final product humidity should be preferably between        0.01%-0.02%.

Step 4. The Manufacturing Process:

-   -   1. Drying of the material for 16 hours by special drier (−50°        C.) desiccant.    -   2. Direct transfer of the material in the drier to the injection        machine, i.e. connecting a drier device directly to the machine.    -   3. Injection molding.    -   4. Curing in an oven for 16 hours.    -   5. Packaging.    -   6. Sterilization in Gamma.

Preferred polyurethane materials for use in the embodiments describedhereinabove include the following materials.

The following materials are manufactured by POLYMER TECHNOLOGY GROUPPTG.

Bionate® polycarbonate-urethane is among the most extensively testedbiomaterials ever developed. The Polymer Technology Group Incorporatedacquired the license to manufacture this thermoplastic elastomer fromCorvita Corporation (who marketed it under the name Corethane®) in 1996.

Carbonate linkages adjacent to hydrocarbon groups give this family ofmaterials oxidative stability, making these polymers attractive inapplications where oxidation is a potential mode of degradation, such asin pacemaker leads, ventricular assist devices, catheters, stents, andmany other biomedical devices. Polycarbonate urethanes were the firstbiomedical polyurethanes promoted for their biostability.

Bionate® polycarbonate-urethane is a thermoplastic elastomer formed asthe reaction product of a hydroxyl terminated polycarbonate, an aromaticdiisocyanate, and a low molecular weightglycol used as a chain extender.

The scope of Bionate PCU's tests—encompassing Histology,Carcinogenicity, Biostability, and Tripartite Biocompatiblity Guidancefor Medical Devices—reassures medical device and implant manufacturersof the material's biocompatibility. This allows biomaterials decisionmakers the ability to choose an efficacious biomaterial that will add tothe cost-effectiveness of the development of their device or implant.Below is a summary of the extensive biocompatibility testing conductedon Bionate PCUs, including its successful completion of a 2-yearcarcinogenicity study.

-   -   Copolymers of silicone with poplyurethanes:    -   PurSil™ Silicone Polyether Urethane    -   CarboSil™ Silicone Polycarbonate Urethane

Silicones have long been known to be biostable and biocompatible in mostimplants, and also frequently have the low hardness and low modulususeful for many device applications. Conventional silicone elastomerscan have very high ultimate elongations, but only low to moderatetensile strengths. Consequently, the toughness of most biomedicalsilicone elastomers is not particularly high. Another disadvantage ofconventional silicone elastomers in device manufacturing is the need forcross-linking to develop useful properties. Once cross-linked, theresulting thermoset silicone cannot be redissolved or remelted.

In contrast, conventional polyurethane elastomers are generallythermoplastic with excellent physical properties. Thermoplastic urethaneelastomers (TPUs) combine high elongation and high tensile strength toform tough, albeit fairly high-modulus elastomers. Aromatic polyetherTPUs can have excellent flex life, tensile strength exceeding 5000 psi,and ultimate elongations greater than 700 percent. They are often usedfor continuously flexing, chronic implants such as ventricular-assistdevices, intraaortic balloons, and artificial heart components. TPUs caneasily be processed by melting or dissolving the polymer to fabricate itinto useful shapes.

The prospect of combining the biocompatibility and biostability ofconventional silicone elastomers with the processability and toughnessof TPUs is an attractive approach to what would appear to be a nearlyideal biomaterial. For instance, it has been reported that silicone actssynergistically with both polycarbonate- and polyether-basedpolyurethanes to improve in vivo and in vitro stability. Inpolycarbonate-based polyurethanes, silicone copolymerization has beenshown to reduce hydrolytic degradation of the carbonate linkage, whereasin polyether urethanes, the covalently bonded silicone seems to protectthe polyether soft segment from oxidative degradation in vivo.

PTG synthesized and patented silicone-polyurethane copolymers bycombining two previously reported methods: copolymerization of silicone(PSX) together with organic (non-silicone) soft segments into thepolymer backbone, and the use of surface-modifying end groups toterminate the copolymer chains. Proprietary synthesis methods makehigh-volume manufacturing possible.

PurSil™ silicone-polyether-urethane and CarboSil™silicone-polycarbonate-urethane are true thermoplastic copolymerscontaining silicone in the soft segment. These high-strengththermoplastic elastomers are prepared through a multi-step bulksynthesis where polydimethylsiloxane (PSX) is incorporated into thepolymer soft segment with polytetramethyleneoxide (PTMO) (PurSil) or analiphatic, hydroxyl-terminated polycarbonate (CarboSil). The hardsegment consists of an aromatic diisocyanate, MDI, with a low molecularweight glycol chain extender. The copolymer chains are then terminatedwith silicone (or other) Surface-Modifying End Groups™. We also offeraliphatic (AL) versions of these materials, with a hard segmentsynthesized from an aliphatic diisocyanate.

Many of these silicone urethanes demonstrate previously unavailablecombinations of physical properties. For example, aromatic siliconepolyetherurethanes have a higher modulus at a given shore hardness thanconventional polyether urethanes—the higher the silicone content, thehigher the modulus (see PurSil Properties). Conversely, the aliphaticsilicone polyetherurethanes have a very low modulus and a high ultimateelongation typical of silicone homopolymers or even natural rubber (seePurSil AL Properties). This makes them very attractive ashigh-performance substitutes for conventional cross-linked siliconerubber. In both the PTMO and PC families, certain polymers have tensilestrengths three to five times higher than conventional siliconebiomaterials.

Surface Modifying End Groups™ (SMEs) are surface-active oligomerscovalently bonded to the base polymer during synthesis. SMEs—whichinclude silicone (S), sulfonate (SO), fluorocarbon (F), polyethyleneoxide (P), and hydrocarbon (H) groups—control surface chemistry withoutcompromising the bulk properties of the polymer. The result is keysurface properties, such as thromboresistance, biostability, andabrasion resistance, are permanently enhanced without additionalpost-fabrication treatments or topical coatings. This patentedtechnology is applicable to a wide range of PTG's polymers.

SMEs provide a series of (biomedical) base polymers that can achieve adesired surface chemistry without the use of additives. Polyurethanesprepared according to PTG's development process couple endgroups to thebackbone polymer during synthesis via a terminal isocyanate group, not ahard segment. The added mobility of endgroups relative to the backboneis thought to facilitate the formation of uniform overlayersby thesurface-active (end) blocks. The use of the surface active endgroupsleaves the original polymer backbone intact so the polymer retainsstrength and processability. The fact that essentially all polymerchains carry the surface-modifying moiety eliminates many of thepotential problems associated with additives.

The SME approach also allows the incorporation of mixed endgroups into asingle polymer. For example, the combination of hydrophobic andhydrophilic endgroups gives the polymer amphipathic characteristics inwhich the hydrophobic versus hydrophilic balance may be easilycontrolled.

The following Materials are manufactured by CARDIOTECH CTE:

CHRONOFLEX®: Biodurable Polyurethane Elastomers are polycarbonatearomatic polyurethanes.

The ChronoFlex® family of medical-grade segmented polyurethaneelastomers have been specifically developed by CardioTech Internationalto overcome the in vivo formation of stress-induced microfissures.

HYDROTHANE™: Hydrophilic Thermoplastic Polyurethanes

HydroThane™ is a family of super-adsorbent, thermoplastic, polyurethanehydrogels ranging in water content from 5 to 25% by weight, HydroThane™is offered as a clear resin in durometer hardness of 80A and 93 Shore A.

The outstanding characteristic of this family of materials is theability to rapidly absorb water, high tensile strength, and highelongation. The result is a polymer having some lubriciouscharacteristics, as well as being inherently bacterial resistant due totheir exceptionally high water content at the surface.

HydroThane™ hydrophilic polyurethane resins are thermoplastic hydrogels,and can be extruded or molded by conventional means. Traditionalhydrogels on the other hand are thermosets and difficult to process.

The following materials are manufactured by THERMEDICS:

Tecothane® (aromatic polyether-based polyurethane), Carbothane®)(aliphatic polycarbonate-based polyurethane), Tecophilic® (high moistureabsorption aliphatic polyether-based polyurethane) and Tecoplast®(aromatic polyether-based polyurethane).

Polyurethanes are designated aromatic or aliphatic on the basis of thechemical nature of the diisocyanate component in their formulation.Tecoflex, Tecophilic and Carbothane resins are manufactured using thealiphatic compound, hydrogenated methylene diisocyanate (HMDI).Tecothane and Tecoplast resins use the aromatic compound methylenediisocyanate (MDI). All the formulations, with the exception ofCarbothane, are formulated using polytetramethylene ether glycol (PTMEG)and 1,4 butanediol chain extender. Carbothane is specifically formulatedwith a polycarbonate diol (PCDO).

These represent the major chemical composition differences among thevarious families. Aromatic and aliphatic polyurethanes share similarproperties that make them outstanding materials for use in medicaldevices. In general, there is not much difference between medical gradealiphatic and aromatic polyurethanes with regard to the followingchemical, mechanical and biological properties:

-   -   High tensile strength (4,000 10,000 psi)    -   High ultimate elongation (250 700%)    -   Wide range of durometer (72 Shore A to 84 Shore D)    -   Good biocompatibility    -   High abrasion resistance    -   Good hydrolytic stability    -   Can be sterilized with ethylene oxide and gamma irradiation    -   Retention of elastomeric properties at low temperature    -   Good melt processing characteristics for extrusion, injection        molding, etc.

With such an impressive array of desirable features, it is no wonderthat both aliphatic and aromatic polyurethanes have become increasinglythe material of choice in the design of medical grade components. Thereare, however, distinct differences between these two families ofpolyurethane that could dictate the selection of one over the other fora particular application:

Yellowing:

In their natural states, both aromatic and aliphatic polyurethanes areclear to very light yellow in color. Aromatics, however, can turn darkyellow to amber as a result of melt processing or sterilization, or evenwith age. Although the primary objection to the discoloration ofaromatic clear tubing or injection molded parts is aesthetic, theyellowing;, which is caused by the formation of a chromophore in the NMIportion of the polymer, does not appear to affect other physicalproperties of the material. Radiopaque grades of Tecothane also exhibitsome discoloration during melt processing or sterilization. However,both standard and custom compounded radiopaque grades of Tecothane havebeen specifically formulated to minimize this discoloration.

Solvent Resistance

Aromatic polyurethanes exhibit better resistance to organic solvents andoils than do aliphatics—especially as compared with low durometer (80 85Shore A) aliphatic, where prolonged contact can lead to swelling of thepolymer and short-term contact can lead to surface tackiness. Whilethese effects become less noticeable at higher durometers, aromaticsexhibit little or no sensitivity upon exposure to the common organicsolvents used in the health care industry.

Softening at Body Temperature

Both aliphatic and aromatic polyether-based polyurethanes softenconsiderably within minutes of insertion in the body. Many devicemanufacturers promote this feature of their urethane products because ofpatient comfort advantage as well as the reduced risk of vasculartrauma. However, this softening effect is less pronounced with aromaticresins than with aliphatic resins.

Melt Processing Temperatures

Tecothane, Tecoplast and Carbothane melt at temperatures considerablyhigher than Tecoflex and Tecophilic. Therefore, processing by eitherextrusion or injection molding puts more heat history into productsmanufactured from Tecothane, Tecoplast and Carbothane. For example,Tecoflex EG-80A and EG-60D resins mold at nozzle temperatures ofapproximately 310° F. and 340° F. respectively.

Tecothane and Carbothane products of equivalent durometers mold atnozzle temperatures in the range of 380° F. to 435° F.

Tecoflex®

A family of aliphatic, polyether-based TPU's. These resins are easy toprocess find do not yellow upon aging. Solution grade versions arecandidates to replace latex.

Tecothane®

A family of aromatic, polyether-based TPU's available over a wide rangeof durometers, colors, and radiopacifiers. One can expect Tecothaneresins to exhibit improved solvent resistance and biostability whencompared with Tecoflex resins of equal durometers.

Carbothane®

A family of aliphatic, polycarbonate-based TPU's available over a widerange of durometers, colors, and radiopacifiers. This type of TPU hasbeen reported to exhibit excellent oxidative stability, a property whichmay equate to excellent long-term biostability. This family, likeTecoflex, is easy to process and does not yellow upon aging.

Tecophilic®

A family of aliphatic, polyether-based TPU's which have been speciallyformulated to absorb equilibrium water contents of up to 150% of theweight of dry resin.

Tecogel, a new member to the Tecophilic family, is a hydrogel that canbe formulated to absorb equilibrium water contents between 500% and2000% of the weight of dry resin. The materials were designed as acoating cast from an ethanol/water solvent system.

Tecoplast®

A family of aromatic, polyether-based TPU's formulated to produce ruggedinjection molded components exhibiting high durometers and heatdeflection temperatures.

Four families of polyurethanes, named Elast-Eon™, are available fromAorTech Biomaterials.

Elast-Eon™1, a Polyhexamethylene oxide (PFMO), aromatic polyurethane, isan improvement on conventional polyurethane in that it has a reducednumber of the susceptible chemical groups. Elast-Eon™2, a Siloxane basedmacrodiol, aromatic polyurethane, incorporates siloxane into the softsegment. Elast-Eon™3, a Siloxane based macrodiol, modified hard segment,aromatic polyurethane, is a variation of Elast-Eon™2 with furtherenhanced flexibility due to incorporation of siloxane into the hardsegment. Elast-Eon™4 is a modified aromatic hard segment polyurethane.

The following materials are manufactured by Bayer Corporation:

-   -   Texin 4210—Thermoplastic polyurethane/polycarbonate blend for        injection molding and extrusion.    -   Texin 4215—Thermoplastic polyurethane/polycarbonate blend for        injection molding and extrusion.    -   Texin 5250—Aromatic polyether-based medical grade with a Shore D        hardness of approximately 50 for injection molding and        extrusion. Complies with 21 CFR 177.1680 and 177.2600.    -   Texin 5286—Aromatic polyether-based medical grade with Shore A        hardness of approximately 86 for injection molding or extrusion.        Complies with 21 CFR 177.1680 and 177.2600.    -   Texin 5290—Aromatic polyether-based medical grade with a Shore A        hardness of approximately 90. Complies with 21 CFR 177.1680 and        177.2600.

It is appreciated that the devices described hereinabove, whilepreferably formed by injection molding of polyurethane, may also beformed by any suitable manufacturing method and may be formed of anysuitable medical grade elastomers. It is further appreciated that any ofthe following manufacturing methods may be utilized: injection moldingincluding inserting inserts, compression molding including insertinginserts, injection—compression molding including inserting inserts,compression molding of prefabricated elements pre-formed by any of theabove methods including inserting inserts, spraying including insertinginserts, dipping including inserting inserts, machining from stock orrods, machining from prefabricated elements including inserting inserts.

It is appreciated by persons skilled in the art that the presentinvention is not limited by what has been particularly shown anddescribed hereinabove. Rather the scope of the present inventionincludes both combinations and subcombinations of various featuresdescribed hereinabove as well as variations and modifications theretowhich would occur to a person of skill in the art upon reading the abovedescription and which are not in the prior art.

1-409. (canceled).
 410. An implantable artificial head resurfacingelement for a mammalian ball and socket joint mounted onto a naturalhead and which defines a wear resistant articulation surface arrangedfor articulation of an articulation surface thereof with a naturalmammalian socket, wherein the size and configuration of an articulationsurface of said artificial head resurfacing element is identical to thatof the natural mammalian socket, in order that the natural head ontowhich artificial head resurfacing element is mounted may articulatetherewith with desired dimensional lubrication clearances and withoutrequiring machining of the natural mammalian socket.
 411. An implantableartificial head resurfacing element according to claim 410, wherein saidartificial head resurfacing element is formed of a resilient material.412. An implantable artificial head resurfacing element according toclaim 410, wherein said artificial head resurfacing element is formed bymolding of polyurethane.
 413. An implantable artificial head resurfacingelement according to claim 410, wherein said artificial head resurfacingelement has an inner concave surface which is configured to directlycontact said natural head in generally static engagement therewith. 414.An implantable artificial head resurfacing element according to claim410, wherein said artificial head resurfacing element is stretch-fitengageable with a bone.
 415. An implantable artificial head resurfacingelement according to claim 410, wherein said artificial head resurfacingelement is snap-fit engageable with a bone.
 416. An implantableartificial head resurfacing element according to claim 410, wherein saidartificial head resurfacing element comprises a unitary element moldedof a single material.
 417. An implantable artificial head resurfacingelement according to claim 410, further comprising at least onedeformation control element.
 418. An implantable artificial headresurfacing element according to claim 417, wherein said artificial headresurfacing element is at least partially formed of material which ismore resilient that the material from which said deformation controlelement is formed.
 419. An implantable artificial head resurfacingelement according to claim 410, further comprising at least onereinforcement element
 420. An implantable artificial head resurfacingelement according to claim 410, wherein said artificial head resurfacingelement is formed of at least a first portion and a second portion, withsaid first portion being formed from a material having differentmechanical properties than the material from which said second portionis formed.
 421. An implantable artificial head resurfacing elementaccording claim 420, wherein said first portion and said second portionare at least partially formed of layers configuration.
 422. Animplantable artificial head resurfacing element according to claim 410,further comprising a fluid absorption portion.
 423. An implantableartificial head resurfacing element according to claim 410, wherein saidartificial head resurfacing element is at least partially formed of atleast an articulation portion and a bone engagement portion and a liquidabsorbing portion there between and wherein said articulation surfacehas formed therein a plurality of thoroughgoing apertures and sideopenings for allowing synovial fluid to pass therethrough forlubrication of the articulation surface.
 424. An implantable artificialhead resurfacing element according to claim 423, wherein said artificialhead resurfacing element is configured such that, when mounted onto anatural joint head and arranged such that application of force to saidjoint causes said articulation portion is resiliently displaced towardsaid bone engagement portion, synovial fluid located between saidarticulation portion and said bone engagement portion to be forcedthrough apertures and openings so as to lie on and over saidarticulation surface and to provide enhanced lubrication for thearticulation of said articulation surface with articulation surface ofsaid natural mammalian socket.
 425. An implantable artificial headresurfacing element according to claim 410, wherein said artificial headresurfacing element is foldable.
 426. An implantable artificial headresurfacing element according to claim 410, wherein said artificial headresurfacing element comprises a resurfacing element precursor ofrelatively reduced dimensions, configured for insertion into a ball andsocket joint environment with reduced disturbance of joint ligaments andsurrounding tissue, said resurfacing element precursor being expandablein situ between existing joint ligaments and surrounding tissue to adesired ball shape.